Method and device for transmitting data in wireless LAN system

ABSTRACT

Proposed are a method and a device for transmitting data in a wireless LAN system. Specifically, a transmission device receives configuration information of a multi-band formed by aggregating first to third bands. The transmission device carries out channel sensing on the first to third bands. The transmission device transmits data to a receiving device on the basis of the result of the channel sensing. The first band comprises a first primary channel and a first secondary channel; the second band comprises a second primary channel and a second secondary channel; and the third band comprises a third primary channel and a third secondary channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2019/007339, filed on Jun. 18, 2019,which claims the benefit of earlier filing date and right of priority toKorean Application Nos. 10-2018-0069656, filed on Jun. 18, 2018, and10-2018-0106741, filed on Sep. 6, 2018, the contents of which are allincorporated by reference herein in their entireties.

BACKGROUND Field

The present specification relates to a scheme of transmitting data in awireless local area network (WLAN) system, and more particularly, to amethod and apparatus for performing channel sensing on a multi-band inthe WLAN system.

Related Art

Discussion for a next-generation wireless local area network (WLAN) isin progress. In the next-generation WLAN, an object is to 1) improve aninstitute of electronic and electronics engineers (IEEE) 802.11 physical(PHY) layer and a medium access control (MAC) layer in bands of 2.4 GHzand 5 GHz, 2) increase spectrum efficiency and area throughput, 3)improve performance in actual indoor and outdoor environments such as anenvironment in which an interference source exists, a denseheterogeneous network environment, and an environment in which a highuser load exists, and the like.

An environment which is primarily considered in the next-generation WLANis a dense environment in which access points (APs) and stations (STAs)are a lot and under the dense environment, improvement of the spectrumefficiency and the area throughput is discussed. Further, in thenext-generation WLAN, in addition to the indoor environment, in theoutdoor environment which is not considerably considered in the existingWLAN, substantial performance improvement is concerned.

In detail, scenarios such as wireless office, smart home, stadium,Hotspot, and building/apartment are largely concerned in thenext-generation WLAN and discussion about improvement of systemperformance in a dense environment in which the APs and the STAs are alot is performed based on the corresponding scenarios.

In the next-generation WLAN, improvement of system performance in anoverlapping basic service set (OBSS) environment and improvement ofoutdoor environment performance, and cellular offloading are anticipatedto be actively discussed rather than improvement of single linkperformance in one basic service set (BSS). Directionality of thenext-generation means that the next-generation WLAN gradually has atechnical scope similar to mobile communication. When a situation isconsidered, in which the mobile communication and the WLAN technologyhave been discussed in a small cell and a direct-to-direct (D2D)communication area in recent years, technical and business convergenceof the next-generation WLAN and the mobile communication is predicted tobe further active.

SUMMARY

The present specification proposes a method and apparatus fortransmitting data in a wireless local area network (WLAN) system.

An example of the present specification proposes a method oftransmitting data.

The present embodiment may be performed in a network environment inwhich a next-generation WLAN system is supported. The next-generationWLAN system is a WLAN system evolved from an 802.11ax system, and maysatisfy backward compatibility with the 802.11ax system.

The present embodiment may be performed in the transmitting device, andthe transmitting device may correspond to a station (STA) supporting anextremely high throughput (EHT) WLAN system. The receiving device of thepresent embodiment may correspond to an access point (AP).

The transmitting device receives setup information on a multi-band inwhich first to third bands are aggregated.

The transmitting device performs channel sensing on the first band tothe third band.

The transmitting device transmits the data to the receiving device,based on a result of the channel sensing.

The first band includes a first primary channel and a first secondarychannel, the second band includes a second primary channel and a secondsecondary channel, and the third band includes a third primary channeland a third secondary channel.

The first band may be a 2.4 GHz band, the second band may be a 5 GHzband, and the third band may be a 6 GHz band.

Although a case where a multi-band is combination of three bands, i.e.,a triple band, is described in the present embodiment, theaforementioned band configuration is only one example, and the WLANsystem may support a variety of number of bands and channels. That is,the present embodiment may also include a case where the multi-band iscombination of two bands and a case where one band is divided into radiofrequencies (RFs) to combine bands supported by respective RFs.

If the first primary channel is busy and a first backoff count (BC)value is not 0, the first BC value is maintained.

If the second primary channel is idle and a second BC value is not 0,the second BC value is set to 0, and the channel sensing is performed onthe second secondary channel.

If the third primary channel is idle and a third BC value is 0, thechannel sensing is performed on the third secondary channel.

For example, if the secondary channel is idle and the third secondarychannel is idle, the data may be transmitted through the second andthird primary channels and the second and third secondary channels. Thatis, the data may be transmitted by aggregating idle channels in thefirst to third bands.

As another example, the third secondary channel may include a firstchannel and a second channel. In this case, if the first channel is busyand the second channel is idle, the first channel may be punctured, andthe data may be transmitted through the second and third primarychannels, the second secondary channel, and the second channel. That is,the data may be transmitted by aggregating idle channels in the first tothird bands. That is, the data may be transmitted by aggregating idlechannels other than the punctured channel in the first to third bands.

As another example, if the first primary channel is busy and the firstBC value is not 0, the first primary channel may be punctured, andchannel sensing may performed on the first secondary channel. If thefirst secondary channel is idle, the data may be transmitted through thefirst secondary channel, the second and third primary channels, and thesecond and third secondary channels. That is, the data may betransmitted by aggregating idle channels other than the puncturedchannel in the first to third bands.

The channel sensing may be performed on the first to third primarychannels and the first to third secondary channels for a pre-setduration. The pre-set duration may be set to a PIFS (PCF (PointCoordination Function) Inter Frame Space), an AIFS (Arbitration InterFrame Space), or one slot.

As another example, the second band may be generated by aggregating afourth band supported by a first radio frequency (RF) and a fifth bandsupported by a second RF. That is, each band may be aggregated bydividing the same band into 2 RFs.

The fourth band may include a fourth primary channel and a fourthsecondary channel, and the fifth band may include a fifth primarychannel and a fifth secondary channel.

If the fourth primary channel is idle and the fourth BC value is not 0,the fourth BC may be set to 0, and the channel sensing may be performedon the fourth secondary channel. If the fifth primary channel is idleand the fifth BC value is 0, the channel sensing may be performed on thefifth secondary channel.

If the fourth secondary channel is idle and the fifth secondary channelis idle, the data may be transmitted through the third primary channel,the third secondary channel, the fourth and fifth primary channels, andthe fourth and fifth secondary channels. That is, idle channels may beaggregated in the first to third bands to transmit the data.

Likewise, the channel sensing may be performed during a pre-set periodfor the fourth to fifth secondary channels. The pre-set period may beset to PIFS (PCF (Point Coordination Function) Inter Frame Space), AIFS(Arbitration Inter Frame Space), or one slot.

In summary, the aforementioned embodiment describes a channel sensingand data transmission method in the presence of BC for each primarychannel.

In a first embodiment, if a primary channel of a specific band is in anidle state but a BC value is not 0, a transmitting device may transmitdata by setting the BC value to 0. The first embodiment may be appliedto the second primary channel. Since the BC value is directly set to 0,there may be a problem in fairness. Advantageously, however, the datacan be directly transmitted in the channel.

In a second embodiment, if the primary channel of the specific band isin an idle state but the BC value is not 0, the transmitting device maytransmit the data by maintaining the BC value. The second embodiment isan embodiment which is not applied to the first to third primarychannels, and a collision probability may increase since data istransmitted even if the BC value is not 0.

In a third embodiment, if the primary channel of the specific band is ina busy state and the BC value is not 0, the transmitting device may nottransmit the data by maintaining the BC value. That is, as in theconventional manner, the transmitting device may persistently wait untilthe BC value is 0 and, when the BC value is 0, may transmit data if thechannel is in the idle state. The third embodiment may be applied to thefirst primary channel. In addition, the third primary channel is also ina state where data can be directly transmitted since the BC value is 0,and thus it can be said that the third embodiment is applied.

In a fourth embodiment, if the primary channel of the specific band isin the busy state and the BC value is not 0, the transmitting device maytransmit the data by maintaining the BC value, by performing puncturingon the primary channel and performing channel sensing on a secondarychannel. Accordingly, when the secondary channel is idle even if theprimary channel is busy, data may be transmitted in a correspondingband, thereby increasing efficiency of the band. In case of a firstchannel and second channel included in the third secondary channel, thefourth embodiment may be applied.

The first BC value may be selected in a first contention window (CW)determined for the first primary channel. The second BC value may beselected in a second CW determined for the second primary channel. Thethird BC value may be selected in a third CW determined for the thirdprimary channel. The fourth BC value may be selected in a fourth CWdetermined for the fourth primary channel. The fifth BC value may beselected in a fifth CW determined for the fifth primary channel.

The transmitting device may receive Block Ack (BA) for the data. The BAmay be received through the same channel as the channel on which thedata is transmitted.

Hereinafter, a signaling scheme for multi-band aggregation will bedescribed. It is described in the present embodiment that setupinformation on a multi-band is received, and signaling may be performedby employing an FST setup scheme.

The transmitting device may transmit a multi-band setup request frame tothe receiving device. The transmitting device may receive a multi-bandsetup response frame from the receiving device.

The transmitting device may transmit a multi-band Ack request frame tothe receiving device. The transmitting device may receive a multi-bandAck response frame from the receiving device.

The transmitting device may include a first station management entity(SME), a first MAC layer management entity (MLME), and a second MLME.The receiving device may include a second SME, a third MLME, and afourth MLME.

The first MLME and the third MLME may be entities supporting the firstband, and the second MLME and the fourth MLME may be entities supportingthe second band.

The multi-band setup request frame and the multi-band setup responseframe may be transmitted/received between the first MLME and the thirdMLME. The multi-band Ack request frame and the multi-band Ack responseframe may be transmitted/received between the second MLME and the fourthMLME.

The first and second SMEs may generate a primitive including amulti-band parameter. The multi-band parameter may include a channelnumber, operating class, and band identifier (ID) designated in themulti-band. The primitive may be transferred to the first to fourthMLMEs.

The multi-band setup scheme includes four states when employing the FSTsetup scheme, and consists of a rule for a method of transitioning fromone state to a next state. The four states are Initial, Setup Completed,Transition Done, and Transition Confirmed.

In the Initial state, the transmitting device and the receiving devicecommunicate in an old band/channel. In this case, upontransmitting/receiving the FST setup request frame and the FST setupresponse frame between the transmitting device and the receiving device,a transition is made to the Setup Complete state, and the transmittingdevice and the receiving device are ready to change a band/channel(s)currently operating. An FST session may be entirely or partiallytransferred to another band/channel.

If a value of LLT included in the FST setup request frame is 0, atransition is made from the Setup Complete state to the Transition Donestate, and the transmitting device and the receiving device may operatein another band/channel.

Both the transmitting device and the receiving device shall communicatesuccessfully in a new band/channel to reach the Transition Confirmedstate. In this case, upon transmitting/receiving the FST Ack requestframe and the FST Ack response frame between the transmitting device andthe receiving device, a transition is made to the Transition Confirmedstate, and the transmitting device and the receiving device establish acomplete connection in the new band/channel.

According to an embodiment proposed in the present specification, acollision probability can be decreased by performing a new channelaccess method for transmitting data on a multi-band, thereby enablingeffective data transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view illustrating the structure of a wirelesslocal area network (WLAN).

FIG. 2 is a diagram illustrating an example of a PPDU used in an IEEEstandard.

FIG. 3 is a diagram illustrating an example of an HE PDDU.

FIG. 4 is a diagram illustrating a layout of resource units (RUs) usedin a band of 20 MHz.

FIG. 5 is a diagram illustrating a layout of resource units (RUs) usedin a band of 40 MHz.

FIG. 6 is a diagram illustrating a layout of resource units (RUs) usedin a band of 80 MHz.

FIG. 7 is a diagram illustrating another example of the HE PPDU.

FIG. 8 is a block diagram illustrating one example of HE-SIG-B accordingto an embodiment.

FIG. 9 illustrates an example of a trigger frame.

FIG. 10 illustrates an example of a common information field.

FIG. 11 illustrates an example of a sub-field being included in a peruser information field.

FIG. 12 illustrates one example of an HE TB PPDU.

FIG. 13 shows multiple channels allocated in a 5 GHz band.

FIG. 14 shows four states of an FST setup protocol.

FIG. 15 shows a procedure of an FST setup protocol.

FIG. 16 shows an example of multi-band aggregation using a 2.4 GHz bandand a 5 GHz band.

FIG. 17 shows an example in which a primary channel exists in each band(or RF) when performing multi-band aggregation.

FIG. 18 shows a BC adjusting method according to the method A1.

FIG. 19 shows an example of a method of transmitting data according tothe method A1+B1.

FIG. 20 shows an example of a BC adjusting method according to themethod A1, in the presence of 2 RFs.

FIG. 21 shows an example of a method of transmitting data according tothe method A1+B1, in the presence of 2 RFs.

FIG. 22 shows an example of a BC adjusting method according to themethod A1, in case of a multi-band in the presence of 2 RFs.

FIG. 23 shows an example of a method of transmitting data according tothe method A1+B1, in case of a multi-band in the presence of 2 RFs.

FIG. 24 shows an example of a method of transmitting data according tothe method A1+B1, including 80 MHz preamble puncturing.

FIG. 25 shows an example of a method of transmitting data according tothe method A1+B1, including 160 MHz preamble puncturing.

FIG. 26 shows an example of a method of transmitting data according tothe method A1+B2.

FIG. 27 shows an example of a method of transmitting data according tothe method A1+B2, including 160 MHz preamble puncturing.

FIG. 28 shows an example of a method of transmitting data according tothe method C.

FIG. 29 shows an example of a method of transmitting data according tothe method C in the presence of 2 RFs.

FIG. 30 shows an example of a method of transmitting data according tothe method C, including 80 MHz preamble puncturing.

FIG. 31 shows an example of a method of transmitting data according tothe method D.

FIG. 32 shows an example of a method of transmitting data according tothe method D, including 80 MHz preamble puncturing.

FIG. 33 is a flowchart illustrating a procedure of transmitting data ina transmitting device according to the present embodiment.

FIG. 34 is a flowchart illustrating a procedure of receiving data in areceiving device according to the present embodiment.

FIG. 35 is a diagram for describing a device for implementing theabove-described method.

FIG. 36 illustrates a more detailed wireless device for implementing theembodiment of the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 is a conceptual view illustrating the structure of a wirelesslocal area network (WLAN).

An upper part of FIG. 1 illustrates the structure of an infrastructurebasic service set (BSS) of institute of electrical and electronicengineers (IEEE) 802.11.

Referring the upper part of FIG. 1, the wireless LAN system may includeone or more infrastructure BSSs (100, 105) (hereinafter, referred to asBSS). The BSSs (100, 105), as a set of an AP and an STA such as anaccess point (AP) (125) and a station (STA1) (100-1) which aresuccessfully synchronized to communicate with each other, are notconcepts indicating a specific region. The BSS (105) may include one ormore STAs (105-1, 105-2) which may be joined to one AP (130).

The BSS may include at least one STA, APs providing a distributionservice, and a distribution system (DS) (110) connecting multiple APs.

The distribution system (110) may implement an extended service set(ESS) (140) extended by connecting the multiple BSSs (100, 105). The ESS(140) may be used as a term indicating one network configured byconnecting one or more APs (125, 130) through the distribution system(110). The AP included in one ESS (140) may have the same service setidentification (SSID).

A portal (120) may serve as a bridge which connects the wireless LANnetwork (IEEE 802.11) and another network (e.g., 802.X).

In the BSS illustrated in the upper part of FIG. 1, a network betweenthe APs (125, 130) and a network between the APs (125, 130) and the STAs(100-1, 105-1, 105-2) may be implemented. However, the network isconfigured even between the STAs without the APs (125, 130) to performcommunication. A network in which the communication is performed byconfiguring the network even between the STAs without the APs (125, 130)is defined as an Ad-Hoc network or an independent basic service set(IBSS).

A lower part of FIG. 1 illustrates a conceptual view illustrating theIBSS.

Referring to the lower part of FIG. 1, the IBSS is a BSS that operatesin an Ad-Hoc mode. Since the IBSS does not include the access point(AP), a centralized management entity that performs a managementfunction at the center does not exist. That is, in the IBSS, STAs(150-1, 150-2, 150-3, 155-4, 155-5) are managed by a distributed manner.In the IBSS, all STAs (150-1, 150-2, 150-3, 155-4, 155-5) may beconstituted by movable STAs and are not permitted to access the DS toconstitute a self-contained network.

The STA as a predetermined functional medium that includes a mediumaccess control (MAC) that follows a regulation of an Institute ofElectrical and Electronics Engineers (IEEE) 802.11 standard and aphysical layer interface for a radio medium may be used as a meaningincluding all of the APs and the non-AP stations (STAs).

The STA may be called various a name such as a mobile terminal, awireless device, a wireless transmit/receive unit (WTRU), user equipment(UE), a mobile station (MS), a mobile subscriber unit, or just a user.

Meanwhile, the term user may be used in various meanings, for example,in wireless LAN communication, this term may be used to signify a STAparticipating in uplink MU MIMO and/or uplink OFDMA transmission.However, the meaning of this term will not be limited only to this.

FIG. 2 is a diagram illustrating an example of a PPDU used in an IEEEstandard.

As illustrated in FIG. 2, various types of PHY protocol data units(PPDUs) may be used in a standard such as IEEE a/g/n/ac, and so on. Indetail, LTF and STF fields include a training signal, SIG-A and SIG-Binclude control information for a receiving station, and a data fieldincludes user data corresponding to a PSDU.

In the embodiment, an improved technique is provided, which isassociated with a signal (alternatively, a control information field)used for the data field of the PPDU. The signal provided in theembodiment may be applied onto high efficiency PPDU (HE PPDU) accordingto an IEEE 802.11ax standard. That is, the signal improved in theembodiment may be HE-SIG-A and/or HE-SIG-B included in the HE PPDU. TheHE-SIG-A and the HE-SIG-B may be represented even as the SIG-A andSIG-B, respectively. However, the improved signal proposed in theembodiment is not particularly limited to an HE-SIG-A and/or HE-SIG-Bstandard and may be applied to control/data fields having various names,which include the control information in a wireless communication systemtransferring the user data.

FIG. 3 is a diagram illustrating an example of an HE PDDU.

The control information field provided in the embodiment may be theHE-SIG-B included in the HE PPDU. The HE PPDU according to FIG. 3 is oneexample of the PPDU for multiple users and only the PPDU for themultiple users may include the HE-SIG-B and the corresponding HE SIG-Bmay be omitted in a PPDU for a single user.

As illustrated in FIG. 3, the HE-PPDU for multiple users (MUs) mayinclude a legacy-short training field (L-STF), a legacy-long trainingfield (L-LTF), a legacy-signal (L-SIG), a high efficiency-signal A(HE-SIG A), a high efficiency-signal-B (HE-SIG B), a highefficiency-short training field (HE-STF), a high efficiency-longtraining field (HE-LTF), a data field (alternatively, an MAC payload),and a packet extension (PE) field. The respective fields may betransmitted during an illustrated time period (that is, 4 or 8 μs).

More detailed description of the respective fields of FIG. 3 will bemade below.

FIG. 4 is a diagram illustrating a layout of resource units (RUs) usedin a band of 20 MHz.

As illustrated in FIG. 4, resource units (RUs) corresponding to tone(that is, subcarriers) of different numbers are used to constitute somefields of the HE-PPDU. For example, the resources may be allocated bythe unit of the RU illustrated for the HE-STF, the HE-LTF, and the datafield.

As illustrated in an uppermost part of FIG. 4, 26 units (that is, unitscorresponding to 26 tones). 6 tones may be used as a guard band in aleftmost band of the 20 MHz band and 5 tones may be used as the guardband in a rightmost band of the 20 MHz band. Further, 7 DC tones may beinserted into a center band, that is, a DC band and a 26-unitcorresponding to each 13 tones may be present at left and right sides ofthe DC band. The 26-unit, a 52-unit, and a 106-unit may be allocated toother bands. Each unit may be allocated for a receiving station, thatis, a user.

Meanwhile, the RU layout of FIG. 4 may be used even in a situation for asingle user (SU) in addition to the multiple users (MUs) and, in thiscase, as illustrated in a lowermost part of FIG. 4, one 242-unit may beused and, in this case, three DC tones may be inserted.

In one example of FIG. 4, RUs having various sizes, that is, a 26-RU, a52-RU, a 106-RU, a 242-RU, and the like are proposed, and as a result,since detailed sizes of the RUs may extend or increase, the embodimentis not limited to a detailed size (that is, the number of correspondingtones) of each RU.

FIG. 5 is a diagram illustrating a layout of resource units (RUs) usedin a band of 40 MHz.

Similarly to a case in which the RUs having various RUs are used in oneexample of FIG. 4, 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, and the like,may be used even in one example of FIG. 5. Further, 5 DC tones may beinserted into a center frequency, 12 tones may be used as the guard bandin the leftmost band of the 40 MHz band and 11 tones may be used as theguard band in the rightmost band of the 40 MHz band.

In addition, as illustrated in FIG. 5, when the RU layout is used forthe single user, the 484-RU may be used. That is, the detailed number ofRUs may be modified similarly to one example of FIG. 4.

FIG. 6 is a diagram illustrating a layout of resource units (RUs) usedin a band of 80 MHz.

Similarly to a case in which the RUs having various RUs are used in oneexample of each of FIG. 4 or 5, 26-RU, 52-RU, 106-RU, 242-RU, 484-RU,and the like, may be used even in one example of FIG. 6. Further, 7 DCtones may be inserted into the center frequency, 12 tones may be used asthe guard band in the leftmost band of the 80 MHz band and 11 tones maybe used as the guard band in the rightmost band of the 80 MHz band. Inaddition, the 26-RU may be used, which uses 13 tones positioned at eachof left and right sides of the DC band.

Moreover, as illustrated in FIG. 6, when the RU layout is used for thesingle user, 996-RU may be used and, in this case, 5 DC tones may beinserted.

Meanwhile, the detailed number of RUs may be modified similarly to oneexample of each of FIG. 4 or FIG. 5.

FIG. 7 is a diagram illustrating another example of the HE PPDU.

A block illustrated in FIG. 7 is another example of describing theHE-PPDU block of FIG. 3 in terms of a frequency.

An illustrated L-STF (700) may include a short training orthogonalfrequency division multiplexing (OFDM) symbol. The L-STF (700) may beused for frame detection, automatic gain control (AGC), diversitydetection, and coarse frequency/time synchronization.

An L-LTF (710) may include a long training orthogonal frequency divisionmultiplexing (OFDM) symbol. The L-LTF (710) may be used for finefrequency/time synchronization and channel prediction.

An L-SIG (720) may be used for transmitting control information. TheL-SIG (720) may include information regarding a data rate and a datalength. Further, the L-SIG (720) may be repeatedly transmitted. That is,a new format, in which the L-SIG (720) is repeated (for example, may bereferred to as R-LSIG) may be configured.

An HE-SIG-A (730) may include the control information common to thereceiving station.

In detail, the HE-SIG-A (730) may include information on 1) a DL/ULindicator, 2) a BSS color field indicating an identify of a BSS, 3) afield indicating a remaining time of a current TXOP period, 4) abandwidth field indicating at least one of 20, 40, 80, 160 and 80+80MHz, 5) a field indicating an MCS technique applied to the HE-SIG-B, 6)an indication field regarding whether the HE-SIG-B is modulated by adual subcarrier modulation technique for MCS, 7) a field indicating thenumber of symbols used for the HE-SIG-B, 8) a field indicating whetherthe HE-SIG-B is configured for a full bandwidth MIMO transmission, 9) afield indicating the number of symbols of the HE-LTF, 10) a fieldindicating the length of the HE-LTF and a CP length, 11) a fieldindicating whether an OFDM symbol is present for LDPC coding, 12) afield indicating control information regarding packet extension (PE),and 13) a field indicating information on a CRC field of the HE-SIG-A,and the like. A detailed field of the HE-SIG-A may be added or partiallyomitted. Further, some fields of the HE-SIG-A may be partially added oromitted in other environments other than a multi-user (MU) environment.

In addition, the HE-SIG-A (730) may be composed of two parts: HE-SIG-A1and HE-SIG-A2. HE-SIG-A1 and HE-SIG-A2 included in the HE-SIG-A may bedefined by the following format structure (fields) according to thePPDU. First, the HE-SIG-A field of the HE SU PPDU may be defined asfollows.

TABLE 1 Two Parts of Number HE-SIG-A Bit Field of bits DescriptionHE-SIG- B0 Format 1 Differentiate an HE SU PPDU and HE ER SU PPDU A1front an HE TB PDDU: Set to 1 for an HE SU PPDU and HE ER SU PPDU B1Beam 1 Set to 1 to indicate that the pre-HE modulated fields of Changethe PPDU are spatially mapped differently from the first symbol of theHE-LTF. Equation (28-6), Equation (28-9), Equation (28-12), Equation(28-14), Equation (28-16) and Equation (28-18) apply if the Beam Changefield is set to 1. Set to 0 to indicate that the pre-HE modulated fieldsof the PPDU are spatially mapped the same way as the first symbol of theHE-LTF on each tone. Equation (28- 8), Equation (28-10), Equation(28-13), Equation (28- 15), Equation (28-17) and Equation (28-19) applyif the Beam Change field is set to 0.(#16803) B2 UL/DL 1 Indicateswhether the PPDU is sent UL or DL. Set to the value indicated by theTXVECTOR parameter UPLINK_FLAG. B3-B6 MCS 4 For an HE SU PPDU: Set tonfor MCSn, where n = 0, 1, 2, . . . , 11 Values 12-15 are reserved For HEER SU PPDU with Bandwidth field set to 0 (242-tone RU): Set to n forMCSn, where n = 0, 1, 2 Values 3-15 are reserved For HE ER SU PPDU withBandwidth field set to 1 (upper frequency 106-tone RU): Set to 0 for MCS0 Values 1-15 are reserved B7 DCM 1 Indicates whether or not DCM isapplied to the Data field for the MCS indicated. If the STBC field is 0,then set to 1 to indicate that DCM is applied to the Data field. NeitherDCM nor STBC shall be applied if(#15489) both the DCM and STBC are setto 1. Set to 0 to indicate that DCM is not applied to the Data field.NOTE-DCM is applied only to HE-MCSs 0, 1, 3 and 4. DCM is applied onlyto 1 and 2 spatial streams. DCM is not applied in combination withSTBC(#15490). B8-B13 BSS Color 6 The BSS Color field is an identifier ofthe BSS. Set to the value of the TXVECTOR parameter BSS_- COLOR. B14Reserved 1 Reserved and set to 1 B15-B18 Spatial Reuse 4 Indicateswhether or not spatial reuse is allowed during the transmission of thisPPDU(#16804). Set to a value from Table 28-21 (Spatial Reuse fieldencoding for an HE SU PPDU, HE ER SU PPDU, and HE MU PPDU), see 27.11.6(SPATIAL_REUSE). Set to SRP_DISALLOW to prohibit SRP-based spatial reuseduring this PPDU. Set to SRP_AND_NON_S- RG_OBSS_PD_PROHIBITED toprohibit both SRP- based spatial reuse and non-SRG OBSS PD-based spa-tial reuse during this PPDU. For the interpretation of other values see27.11.6 (SPATIAL_REUSE) and 27.9 (Spatial reuse operation). B19-B20Bandwidth 2 For an HE SU PPDU: Set to 0 for 20 MHz Set to 1 for 40 MHzSet to 2 for 80 MHz Set to 3 for 160 MHz and 80 + 80 MHz For an HE ER SUPPDU: Set to 0 for 242-tone RU Set to 1 for upper frequency 106-tone RUwithin the primary 20 MHz Values 2 and 3 are reserved B21-B22 GI + LTFSize 2 Indicates the GI duration and HE-LTF size. Set to 0 to indicate a1× HE-LTF and 0.8 μs GI Set to 1 to indicate a 2× HE-LTF and 0.8 μs GISet to 2 to indicate a 2× HE-LTF and 1.6 μs GI Set to 3 to indicate: a4× HE-LTF and 0.8 μs GI if both the DCM and STBC fields are 1. NeitherDCM nor STBC shall be applied if (#Ed) both the DCM and STBC fields areset to 1. a 4× HE-LTF and 3.2 μs GI, otherwise B23-B25 NSTS And 3 If theDoppler field is 0, indicates the number of space- Midamble timestreams. Periodicity Set to the number of space-time streams minus 1 Foran HE ER SU PPDU, values 2 to 7 are reserved If the Doppler field is 1;then B23-B24 indicates the number of space time streams, up to 4, andB25 indi- cates the midamble periodicity. B23-B24 is set to the numberof space time streams minus 1. For an HE ER SU PPDU, values 2 and 3 arereserved B25 is set to 0 if TXVECTOR parameter MEDAM- BLE_PERIODICITY is10 and set to 1 if TXVECTOR parameter MIDAMBLE_PERIODICITY is 20.HE-SIG- B0-B6 TXOP 7 Set to 127 to indicate no duration information A2(HE if (#151491) TXVECTOR parameter TXOP_DURA- SU TION is set toUNSPECIFIED. PPDU) or HE-SIG- Set to a value less than 127 to indicateduration infor- A3 (HE mation for NAV setting and protection of the TXOPas ER SU follows: PPDU) If TXVECTOR parameter TXOP_DURATION is less than512, then BO is set to 0 and B1-B6 is set to lloor(TXOP DURATION/8)(#16277). Otherwise, B0 is set to 1 and B1-B6 is set to floor((TXOP_DURATION - 512 )/128)(#16277). where(#16061) B0 indicates theTXOP length granularity. Set to 0 for 8 μs; otherwise set to 1 for 128μs. B1-B6 indicates the scaled value of the TXOP_DU- RATION B7 Coding 1Indicates whether BCC or LDPC is used: Set to 0 to indicate BCC Set to 1to indicate LDPC B8 LDPC Extra 1 Indicates the presence of the extraOFDM symbol seg- Symbol Seg- ment for LDPC: melt Set to 1 if an extraOFDM symbol segment for LDPC is present Set to 0 if an extra OFDM symbolsegment for LDPC is not present Reserved and set to 1 if the Codingfield is set to 0(#15492). B9 STBC 1 If the DCM field is set to 0, thenset to 1 if space time block coding is used. Neither DCM nor STBC shallbe applied if(#15493) both the DCM field and STBC field are set to 1.Set to 0 otherwise. B10 Beam- 1 Set to 1 if a beamforming steeringmatrix is applied to formed(#180 the waveform in an SU transmission. 48)Set to 0 otherwise. B11-B12 Pre-FEC 2 Indicates the pre-FEC paddingfactor. Padding Fac- Set to 0 to indicate a pre-FEC padding factor of 4tor Set to 1 to indicate a pre-FEC padding factor of 1 Set to 2 toindicate a pre-FEC padding factor of 2 Set to 3 to indicate a pre-FECpadding factor of 3 B13 PE Disambi- 1 Indicates PE disambiguity(#16274)as defined in guity 28.3.12 (Packet extension). B14 Reserved 1 Reservedand set to 1 B15 Doppler 1 Set to 1 if one of the following applies: Thenumber of OFDM symbols in the Data field is larger than the signaledmidamble peri- odicity plus 1 and the midamble is present The number ofOFDM symbols in the Data field is less than or equal to the signaledmid- amble periodicity plus 1 (see 28.3.11.16 Mid- amble), the midambleis not present, but the channel is fast varying. It recommends thatmidamble may be used for the PPDUs of the reverse link. Set to 0otherwise. B16-B19 CRC 4 CRC for bits 0-41 of the HE-SIG-A field (see28.3.10.7.3 (CRC computation)). Bits 0-41 of the HE- SIG-A fieldcorrespond to bits 0-25 of HE-SIG-A1 fol- lowed by bits 0-15 ofHE-SIG-A2). B20-B25 Tail 6 Used to terminate the trellis of theconvolutional decoder. Set to 0.

In addition, the HE-SIG-A field of the HE MU PPDU may be defined asfollows.

TABLE 2 Two Parts of Number HE-SIG-A Bit Field of bits DescriptionHE-SIG-A1 B0 UL/DL 1 Indicates whether the PPDU is sent UL or DL. Set tothe value indicated by the TXVECTOR parameter UPLINK_FLAG.(#16805)NOTE-The TDLS peer can identify the TDLS frame by To DS and From DSfields in the MAC header of the MPDU. B1-B3 SIGB MCS 3 Indicates the MCSof the HE-SIG-B field: Set to 0 for MCS 0 Set to 1 for MCS 1 Set to 2for MCS 2 Set to 3 for MCS 3 Set to 4 for MCS 4 Set to 5 for MCS 5 Thevalues 6 and 7 are reserved B4 SIGB DCM 1 Set to 1 indicates that theHE-SIG-B is modulated with DCM Err the MCS. Set to 0 indicates that theHE-SIG-B is not modulated with DCM for the MCS. NOTE-DCMis onlyapplicable to MCS 0, MCS 1, MCS 3, and MCS 4. B5-B10 BSS Color 6 The BSSColor field is an identifier of the BSS. Set to the value of theTXVECTOR parameter BSS_- COLOR. B11-B14 Spatial Reuse 4 Indicateswhether or not spatial reuse is allowed during the transmission of thisPPDU(#16806). Set to the value of the SPATIAL_REUSE parameter of theTXVECTOR, which contains a value from Table 28-21 (Spatial Reuse fieldencoding for an HE SU PPDU, HE ER SU PPDU, and HE MU PPDU)(see 27.11.6(SPATIAL_REUSE)). Set to SRP_DISALLOW to prohibit SRP-based spatialreuse during this PPDU. Set to SRP_AND_NON_S- RG_OBSS_PD_PROHIBITED toprohibit both SRP- based spatial reuse and non-SRG OBSS PD-based spa-tial reuse during this PPDU. For the interpretation of other values see27.11.6 (SPATIAL_REUSE) and 27.9 (Spatial reuse operation). B15-B17Bandwidth 3 Set to 0 for 20 MHz. Set to 1 for 40 MHz. Set to 2 for 80MHz non-preamble puncturing mode. Set to 3 for 160 MHz and 80 + 80 MHznon-preamble puncturing mode. If the SIGB Compression field is 0: Set to4 for preamble puncturing in 80 MHz, where in the preamble only thesecondary 20 MHz is punc- tured. Set to 5 for preamble puncturing in 80MHz, where in the preamble only one of the two 20 MHz sub- channels insecondary 40 MHz is punctured. Set to 6 for preamble puncturing in 160MHz or 80 + 80 MHz, where in the primary 80 MHz of the preamble only thesecondary 20 MHz is punctured. Set to 7 for preamble puncturing in 160MHz or 80 + 80 MHz, where in the primary 80 MHz of the preamble theprimary 40 MHz is present. If the SIGB Compression field is 1 thenvalues 4-7 are reserved. B18-B21 Number Of 4 If the HE-SIG-B Compressionfield is set to 0, indicates HE-SIG-B the number of OFDM symbols in theHE-SIG-B Symbols Or field:(#15494) MU-MIMO Set to the number of OFDMsymbols in the HE-SIG- Users B field minus 1 if the number of OFDMsymbols M the HE-SIG-B field is less than 16; Set to 15 to indicate thatthe number of OFDM sym- bols in the HE-SIG-B field is equal to 16 ifLonger Than 16 HE SIG-B OFDM Symbols Support sub- field of the HECapabilities element transmitted by at least one recipient STA is 0; Setto 15 to indicate that the number of OFDM sym- bols in the HE-SIG-13field is greater than or equal to 16 if the Longer Than 16 HE SIG-B OFDMSym- bols Support subfield of the HE Capabilities element transmitted byall the recipient STAs are 1 and if the HE-SIG-B data rate is less thanMCS 4 without DCM. The exact number of OFDM symbols in the HE-SIG-Bfield is calculated based on the number of User fields in the HE-SIG-13content channel which is indicated by HE-SIG-B common field in thiscase. If the HE-SIG-B Compression field is set to 1, indicates thenumber of MU-MIMO users and is set to the num- ber of NU-MIMO usersminus 1(#15495). B22 SIGB Com- 1 Set to 0 if the Common field inHE-SIG-B is present. pression Set to 1 if the Common field in HE-SIG-Bis not pres- ent(#16139) B23-B24 GI + LTF Size 2 Indicates the GIduration and HE-LTF size: Set to 0 to indicate a 4× HE-LTF and 0.8 μs GISet to 1 to indicate a 2× HE-LTF and 0.8 μs GI Set to 2 to indicate a 2×HE-LTF and 1.6 μs GI Set to 3 to indicate a 4× HE-LTF and 3.2 μs GI B25Doppler 1 Set to 1 if one of the following applies: The number of OFDMsymbols in the Data field is larger than the signaled midamble peri-odicity plus 1 and the midamble is present The number of OFDM symbols inthe Data field is less than or equal to the signaled mid- ambleperiodicity plus 1 (see 28.3.11.16 Mid- amble), the midamble is notpresent, but the channel is fast varying. It recommends that midamblemay be used for the PPDUs of the reverse link. Set to 0 otherwise.HE-SIG- B0-B6 TXOP 7 Set to 127 to indicate no duration in informationA2 if (#15496) TXVECTOR parameter TXOP_DURA- TION is set to UNSPECIFIED.Set to a value less than 127 to indicate duration infor- mation for NAVsetting and protection of the TXOP as follows: If TXVECTOR parameterTXOP_DURATION is less than 512, then B0 is set to 0 and B1-B6 is set tofloor(TXOP_DURATION/8)(#16277). Otherwise, B0 is set to 1 and B1-B6 isset to floor ((TXOP_DURATION - 512 )/128)(#16277). where(#16061) B0indicates the TXOP length granularity. Set to 0 for 8 μs; otherwise setto 1 for 128 μs. B1-B6 indicates the scaled value of the TXOP_DU- RATIONB7 Reserved 1 Reserved and set to 1 B8-B10 Number of 3 If the Dopplerfield is set to 0(#15497), indicates the HE-LTF number of HE-LTFsymbols: SymbolsAnd Set to 0 for 1 HE-LTF symbol Midamble Set to 1 for 2HE-I.TF symbols Periodicity Set to 2 for 4 HE-LTF symbols Set to 3 for 6HE-LTF symbols Set to 4 for 8 HE-LTF symbols Other values are reserved.If the Doppler field is set to 1(#15498), B8-B9 indi- cates the numberof HE-LTF symbols(#16056) and B10 indicates rnidamble periodicity: B8-B9is encoded as follows: 0 indicates 1 HE-LTF symbol 1 indicates 2 HE-LTFsymbols 2 indicates 4 HE-LTF symbols 3 is reserved B10 is set to 0 ifthe TXVECTOR parameter MIDAM- BLE_PERIODICITY is 10 and set to 1 if theTXVEC- TOR parameter PREAMBLE_PERIODICITY is 20. B11 LDPC Extra 1Indication of the presence of the extra OFDM symbol Symbol Seg- segmentfor LDPC. ment Set to 1 if an extra OFDM symbol segment for LDPC ispresent. Set to 0 otherwise. B12 STBC 1 In an HE MU PPDU where each RUincludes no more than 1 user, set to 1 to indicate all RUs are STBCencoded in the payload, set to 0 to indicate all RUs are not STBCencoded in the payload. STBC does not apply to HE-SIG-B. STBC is notapplied if one or more RUs are used for MU-MIMO allocation. (#15661)B13-B14 Pre-FEC 2 Indicates the pre-FEC padding factor. Padding Fac- Setto 0 to indicate a pre-FEC padding factor of 4 tor Set to 1 to indicatea pre-FEC padding factor of 1 Set to 2 to indicate a pre-FEC paddingfactor of 2 Set to 3 to indicate a pre-FEC padding factor of 3 B15 PEDisambi- 1 Indicates PE disambiguity(#16274) as defmed in guity 28.3.12(Packet extension). B16-B19 CRC 4 CRC for bits 0-41 of the HE-SIG-Afield (see 28.3.10.7.3 (CRC computation)). Bits 0-41 of the HE- SIG-Afield correspond to bits 0-25 of HE-SIG-A1 fol- lowed by bits 0-15 ofHE-SIG-A2). B20-B25 Tail 6 Used to terminate the trellis of theconvolutional decoder. Set to 0.

In addition, the HE-SIG-A field of the HE TB PPDU may be defined asfollows.

TABLE 3 Two Parts of Number HE-SIG-A Bit Field of bits DescriptionHE-SIG-A1 B0 Format 1 Differentiate an HE SU PPDU and HE ER SU PPDU froman HE TB PPDU: Set to 0 for an HE TB PPDU B1-B6 BSS Color 6 The BSSColor field is an identifier of the BSS. Set to the value of theTXVECTOR parameter BSS_- COLOR. B7-B10 Spatial Reuse 4 Indicates whetheror not spatial reuse is allowed in a 1 subband of the PPDU during thetransmission of this PPDIJ, and if allowed, indicates a value that isused to determine a limit on the transmit power of a spatial reusetransmission. If the Bandwidth field indicates 20 MHz, 40 MHz, or 80 MHzthen this Spatial Reuse field applies to the first 20 MHz subband. Ifthe Bandwidth field indicates 160/80 + 80 MHz then this Spatial Reusefield applies to the first 40 MHz sub- band of the 160 MHz operatingband. Set to the value of the SPATIAL_REUSE(1) parameter of theTXVECTOR, which contains a value from Table 28-22 (Spatial Reuse fieldencoding for an HE TB PPDU) for an HE TB PPDU (see 27.11.6 (SPA-TIAL_REUSE)). Set to SRP_DISALLOW to prohibit SRP-based spatial reuseduring this PPDIJ. Set to SRP_AND NON_S- RG_OBSS_PD_PROBIBITED toprohibit both SRP- based spatial reuse and non-SRG OBSS PD-based spa-tial reuse during this PPDU. For the interpretation of other values see27.11.6 (SPATIAL_REUSE) and 27.9 (Spatial reuse operation). B11-B14Spatial Reuse 4 Indicates whether or not spatial reuse is allowed in a 2subband of the PPDU during the transmission of this PPDU, and ifallowed, indicates a value that is used to determine a limit on thetransmit power of a spatial reuse transmission. If the Bandwidth fieldindicates 20 MHz, 40 MHz, or 80 MHz: This Spatial Reuse field applies tothe second 20 MHz subband. If(#Ed) the STA operating channel width is 20MHz, then this field is set to the same value as Spatial Reuse 1 field.If(#Ed) the STA operating channel width is 40 MHz in the 2.4 GHz band,this field is set to the same value as Spatial Reuse 1 field. If theBandwidth field indicates 160/80 + 80 MHz the this Spatial Reuse fieldapplies to the second 40 MHz subband of the 160 MHz operating band. Setto the value of the SPATIAL_REUSE(2) parameter of the TXVECTOR, whichcontains a value from Table 28-22 (Spatial Reuse field encoding for anHE TB PPDU) for an HE TB PPDU (see 27.11.6 (SPA- TIAL_REUSE)). Set toSRP_DISALLOW to prohibit SRP-based spatial reuse during this PPDU. Setto SRP_AND_NON_S- RG_OBSS_PD_PROHIBITED to prohibit both SRP- basedspatial reuse and non-SRG OBSS PD-based spa- tial reuse during thisPPDU. For the interpretation of other values see 27.11.6 (SPATIAL_REUSE)and 27.9 (Spatial reuse operation). B15-B18 Spatial Reuse 4 Indicateswhether or not spatial reuse is allowed in a 3 subband of the PPDUduring the transmission of this PPDU, and if allowed, indicates a valuethat is used to determine a limit on the transmit power of a spatialreuse transmission. If the Bandwidth field indicates 20 MHz, 40 MHz or80 MHz: This Spatial Reuse field applies to the third 20 MHz subband.IF(#Ed) the STA operating channel width is 20 MHz or 40 MHz, this fieldis set to the same value as Spa- tial Reuse 1 field. If the Bandwidthfield indicates 160/80 + 80MHz: This Spatial Reuse field applies to thethird 40 MHz subband of the 160 MHz operating band. If(#Ed) the STAoperating channel width is 80 + 80 MHz, this field is set to the samevalue as Spatial Reuse 1 field. Set to the value of the SPATIAL_REUSE(3)parameter of the TXVECTOR, which contains a value from Table 28-22(Spatial Reuse field encoding for an HE TB PPDU) for an HE TB PPDU (see27.11.6 (SPA- TIAL_REUSE)). Set to SRP_DISALLOW to prohibit SRP-basedspatial reuse during this PPDU. Set to SRP_AND_NON_S-RG_OBSS_PD_PROHIBITED to prohibit both SRP- based spatial reuse andnon-SRG OBSS PD-based spa- tial reuse during this PPDU. For theinterpretation of other values see 27.11.6 (SPATIAL REUSE) and 27.9(Spatial reuse operation). B19-B22 Spatial Reuse 4 Indicates whether ornot spatial reuse is allowed in a 4 subband of the PPDU during thetransmission of this PPDU, and if allowed, indicates a value that isused to determine a limit on the transmit power of a spatial reusetransmission. If the Bandwidth field indicates 20 MHz, 40 MHz or 80 MHz:This Spatial Reuse field applies to the fourth 20 MHz subband. If(#Ed)the STA operating channel width is 20 MHz, then this field is set to thesame value as Spatial Reuse 1 field. If(#Ed) the STA operating channelwidth is 40 MHz, then this field is set to the mine value as SpatialReuse 2 field. If the Bandwidth field indicates 160/80 + 80 MHz: ThisSpatial Reuse field applies to the fourth 40 MHz subband of the 160 MHzoperating band. If(#Ed) the STA operating channel width is 80 + 80 MHz,then this field is set to same value as Spatial Reuse 2 field. Set tothe value of the SPATIAL_REUSE(4) parameter of the TXVECTOR, whichcontains a value from Table 28-22 (Spatial Reuse field encoding for anHE TB PPDU) for an HE TB PPDU (see 27.11.6 (SPA- TIAL_REUSE)). Set toSRP_DISAELOW to prohibit SRP-based spatial reuse during this PPDU. Setto SRP_AND_NON_S- RG_OBSS_PD_PROHIBITED to prohibit both SRP- basedspatial reuse and non-SRG OBSS PD-based spa- tial reuse during thisPPDU. For the interpretation of other values see 27.11.6 (SPATIAL REUSE)and 27.9 (Spatial reuse operation). B23 Reserved 1 Reserved and setto 1. NOTE-Unlike other Reserved fields in HE-SIG-A of the HE TB PPDU,B23 does not have a corresponding bit in the Trigger frame. B24-B25Bandwidth 2 (#16003)Set to 0 for 20 MHz Set to 1 for 40 MHz Set to 2 for80 MHz Set to 3 for 160 MHz and 80 + 80 MHz HE-SIG- B0-B6 TXOP 7 Set to127 to indicate no duration information A2 if(415499) TX VECTORparameter TXOP_DURA- TION is set to UNSPECIFIED. Set to a value lessthan 127 to indicate duration infor- mation for NAV setting andprotection of the TXOP as follows: If TXVECTOR parameter TXOP_DURATIONis less than 512, then B0 is set to (land B1-B6 is set tofloor(TXOP_DURATION/8)(#16277). Otherwise, B0 is set to 1 and B1-B6 isset to floor ((TXOP DURATION - 512)/128)(#16277). where(#16061) B0indicates the TXOP length granularity. Set to 0 for 8 μs; otherwise setto 1 for 128 μs. B1-B6 indicates the scaled value of the TXOP_DU- RATIONB7-B15 Reserved 9 Reserved and set to value indicated in the UL HE-SIG-A2 Reserved subfield in the Trigger frame. B16-B19 CRC 4 CRC of bits0-41 of the HE-SIG-A field. See 28.3.10.7.3 (CRC computation). Bits 0-41of the HE- SIG-A field correspond to bits 0-25 of HE-SIG-A1 fol- lowedby bits 0-15 of HE-SIG-A2). B20-B25 Tail 6 Used to terminate the trellisof the convolutional decoder. Set to 0.

An HE-SIG-B (740) may be included only in the case of the PPDU for themultiple users (MUs) as described above. Principally, an HE-SIG-A (750)or an HE-SIG-B (760) may include resource allocation information(alternatively, virtual resource allocation information) for at leastone receiving STA.

FIG. 8 is a block diagram illustrating one example of HE-SIG-B accordingto an embodiment.

As illustrated in FIG. 8, the HE-SIG-B field includes a common field ata frontmost part and the corresponding common field is separated from afield which follows therebehind to be encoded. That is, as illustratedin FIG. 8, the HE-SIG-B field may include a common field including thecommon control information and a user-specific field includinguser-specific control information. In this case, the common field mayinclude a CRC field corresponding to the common field, and the like andmay be coded to be one BCC block. The user-specific field subsequentthereafter may be coded to be one BCC block including the “user-specificfield” for 2 users and a CRC field corresponding thereto as illustratedin FIG. 8.

A previous field of the HE-SIG-B (740) may be transmitted in aduplicated form on a MU PPDU. In the case of the HE-SIG-B (740), theHE-SIG-B (740) transmitted in some frequency band (e.g., a fourthfrequency band) may even include control information for a data fieldcorresponding to a corresponding frequency band (that is, the fourthfrequency band) and a data field of another frequency band (e.g., asecond frequency band) other than the corresponding frequency band.Further, a format may be provided, in which the HE-SIG-B (740) in aspecific frequency band (e.g., the second frequency band) is duplicatedwith the HE-SIG-B (740) of another frequency band (e.g., the fourthfrequency band). Alternatively, the HE-SIG B (740) may be transmitted inan encoded form on all transmission resources. A field after the HE-SIGB (740) may include individual information for respective receiving STAsreceiving the PPDU.

The HE-STF (750) may be used for improving automatic gain controlestimation in a multiple input multiple output (MIMO) environment or anOFDMA environment.

The HE-LTF (760) may be used for estimating a channel in the MIMOenvironment or the OFDMA environment.

The size of fast Fourier transform (FFT)/inverse fast Fourier transform(IFFT) applied to the HE-STF (750) and the field after the HE-STF (750),and the size of the FFT/IFFT applied to the field before the HE-STF(750) may be different from each other. For example, the size of theFFT/IFFT applied to the HE-STF (750) and the field after the HE-STF(750) may be four times larger than the size of the FFT/IFFT applied tothe field before the HE-STF (750).

For example, when at least one field of the L-STF (700), the L-LTF(710), the L-SIG (720), the HE-SIG-A (730), and the HE-SIG-B (740) onthe PPDU of FIG. 7 is referred to as a first field, at least one of thedata field (770), the HE-STF (750), and the HE-LTF (760) may be referredto as a second field. The first field may include a field associatedwith a legacy system and the second field may include a field associatedwith an HE system. In this case, the fast Fourier transform (FFT) sizeand the inverse fast Fourier transform (IFFT) size may be defined as asize which is N (N is a natural number, e.g., N=1, 2, and 4) timeslarger than the FFT/IFFT size used in the legacy wireless LAN system.That is, the FFT/IFFT having the size may be applied, which is N (=4)times larger than the first field of the HE PPDU. For example, 256FFT/IFFT may be applied to a bandwidth of 20 MHz, 512 FFT/IFFT may beapplied to a bandwidth of 40 MHz, 1024 FFT/IFFT may be applied to abandwidth of 80 MHz, and 2048 FFT/IFFT may be applied to a bandwidth ofcontinuous 160 MHz or discontinuous 160 MHz.

In other words, a subcarrier space/subcarrier spacing may have a sizewhich is 1/N times (N is the natural number, e.g., N=4, the subcarrierspacing is set to 78.125 kHz) the subcarrier space used in the legacywireless LAN system. That is, subcarrier spacing having a size of 312.5kHz, which is legacy subcarrier spacing may be applied to the firstfield of the HE PPDU and a subcarrier space having a size of 78.125 kHzmay be applied to the second field of the HE PPDU.

Alternatively, an IDFT/DFT period applied to each symbol of the firstfield may be expressed to be N (=4) times shorter than the IDFT/DFTperiod applied to each data symbol of the second field. That is, theIDFT/DFT length applied to each symbol of the first field of the HE PPDUmay be expressed as 3.2 μs and the IDFT/DFT length applied to eachsymbol of the second field of the HE PPDU may be expressed as 3.2 μs*4(=12.8 μs). The length of the OFDM symbol may be a value acquired byadding the length of a guard interval (GI) to the IDFT/DFT length. Thelength of the GI may have various values such as 0.4 μs, 0.8 μs, 1.6 μs,2.4 μs, and 3.2 μs.

For simplicity in the description, in FIG. 7, it is expressed that afrequency band used by the first field and a frequency band used by thesecond field accurately coincide with each other, but both frequencybands may not completely coincide with each other, in actual. Forexample, a primary band of the first field (L-STF, L-LTF, L-SIG,HE-SIG-A, and HE-SIG-B) corresponding to the first frequency band may bethe same as the most portions of a frequency band of the second field(HE-STF, HE-LTF, and Data), but boundary surfaces of the respectivefrequency bands may not coincide with each other. As illustrated inFIGS. 4 to 6, since multiple null subcarriers, DC tones, guard tones,and the like are inserted during arranging the RUs, it may be difficultto accurately adjust the boundary surfaces.

The user (e.g., a receiving station) may receive the HE-SIG-A (730) andmay be instructed to receive the downlink PPDU based on the HE-SIG-A(730). In this case, the STA may perform decoding based on the FFT sizechanged from the HE-STF (750) and the field after the HE-STF (750). Onthe contrary, when the STA may not be instructed to receive the downlinkPPDU based on the HE-SIG-A (730), the STA may stop the decoding andconfigure a network allocation vector (NAV). A cyclic prefix (CP) of theHE-STF (750) may have a larger size than the CP of another field and theduring the CP period, the STA may perform the decoding for the downlinkPPDU by changing the FFT size.

Hereinafter, in the embodiment of the present disclosure, data(alternatively, or a frame) which the AP transmits to the STA may beexpressed as a terms called downlink data (alternatively, a downlinkframe) and data (alternatively, a frame) which the STA transmits to theAP may be expressed as a term called uplink data (alternatively, anuplink frame). Further, transmission from the AP to the STA may beexpressed as downlink transmission and transmission from the STA to theAP may be expressed as a term called uplink transmission.

In addition, a PHY protocol data unit (PPDU), a frame, and datatransmitted through the downlink transmission may be expressed as termssuch as a downlink PPDU, a downlink frame, and downlink data,respectively. The PPDU may be a data unit including a PPDU header and aphysical layer service data unit (PSDU) (alternatively, a MAC protocoldata unit (MPDU)). The PPDU header may include a PHY header and a PHYpreamble and the PSDU (alternatively, MPDU) may include the frame orindicate the frame (alternatively, an information unit of the MAC layer)or be a data unit indicating the frame. The PHY header may be expressedas a physical layer convergence protocol (PLCP) header as another termand the PHY preamble may be expressed as a PLCP preamble as anotherterm.

Further, a PPDU, a frame, and data transmitted through the uplinktransmission may be expressed as terms such as an uplink PPDU, an uplinkframe, and uplink data, respectively.

In the wireless LAN system to which the embodiment of the presentdescription is applied, the total bandwidth may be used for downlinktransmission to one STA and uplink transmission to one STA. Further, inthe wireless LAN system to which the embodiment of the presentdescription is applied, the AP may perform downlink (DL) multi-user (MU)transmission based on multiple input multiple output (MU MIMO) and thetransmission may be expressed as a term called DL MU MIMO transmission.

In addition, in the wireless LAN system according to the embodiment, anorthogonal frequency division multiple access (OFDMA) based transmissionmethod is preferably supported for the uplink transmission and/ordownlink transmission. That is, data units (e.g., RUs) corresponding todifferent frequency resources are allocated to the user to performuplink/downlink communication. In detail, in the wireless LAN systemaccording to the embodiment, the AP may perform the DL MU transmissionbased on the OFDMA and the transmission may be expressed as a termcalled DL MU OFDMA transmission. When the DL MU OFDMA transmission isperformed, the AP may transmit the downlink data (alternatively, thedownlink frame and the downlink PPDU) to the plurality of respectiveSTAs through the plurality of respective frequency resources on anoverlapped time resource. The plurality of frequency resources may be aplurality of subbands (alternatively, subchannels) or a plurality ofresource units (RUs). The DL MU OFDMA transmission may be used togetherwith the DL MU MIMO transmission. For example, the DL MU MIMOtransmission based on a plurality of space-time streams (alternatively,spatial streams) may be performed on a specific subband (alternatively,subchannel) allocated for the DL MU OFDMA transmission.

Further, in the wireless LAN system according to the embodiment, uplinkmulti-user (UL MU) transmission in which the plurality of STAs transmitsdata to the AP on the same time resource may be supported. Uplinktransmission on the overlapped time resource by the plurality ofrespective STAs may be performed on a frequency domain or a spatialdomain.

When the uplink transmission by the plurality of respective STAs isperformed on the frequency domain, different frequency resources may beallocated to the plurality of respective STAs as uplink transmissionresources based on the OFDMA. The different frequency resources may bedifferent subbands (alternatively, subchannels) or different resourcesunits (RUs). The plurality of respective STAs may transmit uplink datato the AP through different frequency resources. The transmission methodthrough the different frequency resources may be expressed as a termcalled a UL MU OFDMA transmission method.

When the uplink transmission by the plurality of respective STAs isperformed on the spatial domain, different time-space streams(alternatively, spatial streams) may be allocated to the plurality ofrespective STAs and the plurality of respective STAs may transmit theuplink data to the AP through the different time-space streams. Thetransmission method through the different spatial streams may beexpressed as a term called a UL MU MIMO transmission method.

The UL MU OFDMA transmission and the UL MU MIMO transmission may be usedtogether with each other. For example, the UL MU MIMO transmission basedon the plurality of space-time streams (alternatively, spatial streams)may be performed on a specific subband (alternatively, subchannel)allocated for the UL MU OFDMA transmission.

In the legacy wireless LAN system which does not support the MU OFDMAtransmission, a multi-channel allocation method is used for allocating awider bandwidth (e.g., a 20 MHz excess bandwidth) to one terminal. Whena channel unit is 20 MHz, multiple channels may include a plurality of20 MHz-channels. In the multi-channel allocation method, a primarychannel rule is used to allocate the wider bandwidth to the terminal.When the primary channel rule is used, there is a limit for allocatingthe wider bandwidth to the terminal. In detail, according to the primarychannel rule, when a secondary channel adjacent to a primary channel isused in an overlapped BSS (OBSS) and is thus busy, the STA may useremaining channels other than the primary channel. Therefore, since theSTA may transmit the frame only to the primary channel, the STA receivesa limit for transmission of the frame through the multiple channels.That is, in the legacy wireless LAN system, the primary channel ruleused for allocating the multiple channels may be a large limit inobtaining a high throughput by operating the wider bandwidth in acurrent wireless LAN environment in which the OBSS is not small.

In order to solve the problem, in the embodiment, a wireless LAN systemis disclosed, which supports the OFDMA technology. That is, the OFDMAtechnique may be applied to at least one of downlink and uplink.Further, the MU-MIMO technique may be additionally applied to at leastone of downlink and uplink. When the OFDMA technique is used, themultiple channels may be simultaneously used by not one terminal butmultiple terminals without the limit by the primary channel rule.Therefore, the wider bandwidth may be operated to improve efficiency ofoperating a wireless resource.

As described above, in case the uplink transmission performed by each ofthe multiple STAs (e.g., non-AP STAs) is performed within the frequencydomain, the AP may allocate different frequency resources respective toeach of the multiple STAs as uplink transmission resources based onOFDMA. Additionally, as described above, the frequency resources eachbeing different from one another may correspond to different subbands(or sub-channels) or different resource units (RUs).

The different frequency resources respective to each of the multipleSTAs are indicated through a trigger frame.

FIG. 9 illustrates an example of a trigger frame. The trigger frame ofFIG. 9 allocates resources for Uplink Multiple-User (MU) transmissionand may be transmitted from the AP. The trigger frame may be configuredas a MAC frame and may be included in the PPDU. For example, the triggerframe may be transmitted through the PPDU shown in FIG. 3, through thelegacy PPDU shown in FIG. 2, or through a certain PPDU, which is newlydesigned for the corresponding trigger frame. In case the trigger frameis transmitted through the PPDU of FIG. 3, the trigger frame may beincluded in the data field shown in the drawing.

Each of the fields shown in FIG. 9 may be partially omitted, or otherfields may be added. Moreover, the length of each field may be varieddifferently as shown in the drawing.

A Frame Control field (910) shown in FIG. 9 may include informationrelated to a version of the MAC protocol and other additional controlinformation, and a Duration field (920) may include time information forconfiguring a NAV or information related to an identifier (e.g., AID) ofthe user equipment.

Also, the RA field (930) includes address information of a receiving STAof the corresponding trigger frame and may be omitted if necessary. TheTA field (940) includes address information of an STA triggering thecorresponding trigger frame (for example, an AP), and the commoninformation field (950) includes common control information applied to areceiving STA that receives the corresponding trigger frame. Forexample, a field indicating the length of the L-SIG field of the UL PPDUtransmitted in response to the corresponding trigger frame orinformation controlling the content of the SIG-A field (namely, theHE-SIG-A field) of the UL PPDU transmitted in response to thecorresponding trigger frame may be included. Also, as common controlinformation, information on the length of the CP of the UP PPDUtransmitted in response to the corresponding trigger frame orinformation on the length of the LTF field may be included.

Also, it is preferable to include a per user information field (960 #1to 960 #N) corresponding to the number of receiving STAs that receivethe trigger frame of FIG. 9. The per user information field may bereferred to as an “RU allocation field”.

Also, the trigger frame of FIG. 9 may include a padding field (970) anda frame check sequence field (980).

It is preferable that each of the per user information fields (960 #1 to960 #N) shown in FIG. 9 includes a plurality of subfields.

FIG. 10 illustrates an example of a common information field. Among thesubfields of FIG. 10, some may be omitted, and other additionalsubfields may also be added. Additionally, the length of each of thesubfields shown in the drawing may be varied.

The trigger type field (1010) of FIG. 10 may indicate a trigger framevariant and encoding of the trigger frame variant. The trigger typefield (1010) may be defined as follows.

TABLE 4 Trigger Type subfield value Trigger frame variant 0 Basic 1Beamforming Report Poll (BFRP) 2 MU-BAR 3 MU-RTS 4 Buffer Status ReportPoll (BSRP) 5 GCR MU-BAR 6 Bandwidth Query Report Poll (BQRP) 7 NDPFeedback Report Poll (NFRP) 8-15 Reserved

The UL BW field (1020) of FIG. 10 indicates bandwidth in the HE-SIG-Afield of an HE Trigger Based (TB) PPDU. The UL BW field (1020) may bedefined as follows.

TABLE 5 UL BW subfield value Description 0 20 MHz 1 40 MHz 2 80 MHz 380 + 80 MHz or 160 MHz

The Guard Interval (GI) and LTF type fields (1030) of FIG. 10 indicatethe GI and HE-LTF type of the HE TB PPDU response. The GI and LTF typefield (1030) may be defined as follows.

TABLE 6 GI And LTF field value Description 0 1× HE-LTF + 1 6 μs GI 1 2×HE-LTF + 1.6 μs GI 2 4× HE-LTF + 3 2 μs GI(#15968) 3 Reserved

Also, when the GI and LTF type fields (1030) have a value of 2 or 3, theMU-MIMO LTF mode field (1040) of FIG. 10 indicates the LTF mode of a ULMU-MIMO HE TB PPDU response. At this time, the MU-MIMO LTF mode field(1040) may be defined as follows.

If the trigger frame allocates an RU that occupies the whole HE TB PPDUbandwidth and the RU is allocated to one or more STAs, the MU-MIMO LTFmode field (1040) indicates one of an HE single stream pilot HE-LTF modeor an HE masked HE-LTF sequence mode.

If the trigger frame does not allocate an RU that occupies the whole HETB PPDU bandwidth and the RU is not allocated to one or more STAs, theMU-MIMO LTF mode field (1040) indicates the HE single stream pilotHE-LTF mode. The MU-MIMO LTF mode field (1040) may be defined asfollows.

TABLE 7 MU-MIMO LTF subfield value Description 0 HE single stream pilotHE-LTF mode 1 HE masked HE-LTF sequence mode

FIG. 11 illustrates an example of a subfield being included in a peruser information field. Among the subfields of FIG. 11, some may beomitted, and other additional subfields may also be added. Additionally,the length of each of the subfields shown in the drawing may be varied.

The User Identifier field of FIG. 11 (or AID12 field, 1110) indicatesthe identifier of an STA (namely, a receiving STA) corresponding to peruser information, where an example of the identifier may be the whole orpart of the AID.

Also, an RU Allocation field (1120) may be included. In other words,when a receiving STA identified by the User Identifier field (1110)transmits a UL PPDU in response to the trigger frame of FIG. 9, thecorresponding UL PPDU is transmitted through an RU indicated by the RUAllocation field (1120). In this case, it is preferable that the RUindicated by the RU Allocation field (1120) indicates the RUs shown inFIGS. 4, 5, and 6. A specific structure of the RU Allocation field(1120) will be described later.

The subfield of FIG. 11 may include a (UL FEC) coding type field (1130).The coding type field (1130) may indicate the coding type of an uplinkPPDU transmitted in response to the trigger frame of FIG. 9. Forexample, when BCC coding is applied to the uplink PPDU, the coding typefield (1130) may be set to ‘1’, and when LDPC coding is applied, thecoding type field (1130) may be set to ‘0’.

Additionally, the subfield of FIG. 11 may include a UL MCS field (1140).The MCS field (1140) may indicate an MCS scheme being applied to theuplink PPDU that is transmitted in response to the trigger frame of FIG.9.

Also, the subfield of FIG. 11 may include a Trigger Dependent User Infofield (1150). When the Trigger Type field (1010) of FIG. 10 indicates abasic trigger variant, the Trigger Dependent User Info field (1150) mayinclude an MPDU MU Spacing Factor subfield (2 bits), a TID AggregateLimit subfield (3 bits), a Reserved field (1 bit), and a Preferred ACsubfield (2 bits).

Hereinafter, the present disclosure proposes an example of improving acontrol field included in a PPDU. The control field improved accordingto the present disclosure includes a first control field includingcontrol information required to interpret the PPDU and a second controlfield including control information for demodulate the data field of thePPDU. The first and second control fields may be used for variousfields. For example, the first control field may be the HE-SIG-A (730)of FIG. 7, and the second control field may be the HE-SIG-B (740) shownin FIGS. 7 and 8.

Hereinafter, a specific example of improving the first or the secondcontrol field will be described.

In the following example, a control identifier inserted to the firstcontrol field or a second control field is proposed. The size of thecontrol identifier may vary, which, for example, may be implemented with1-bit information.

The control identifier (for example, a 1-bit identifier) may indicatewhether a 242-type RU is allocated when, for example, 20 MHztransmission is performed. As shown in FIGS. 4 to 6, RUs of varioussizes may be used. These RUs may be divided broadly into two types. Forexample, all of the RUs shown in FIGS. 4 to 6 may be classified into26-type RUs and 242-type RUs. For example, a 26-type RU may include a26-RU, a 52-RU, and a 106-RU while a 242-type RU may include a 242-RU, a484-RU, and a larger RU.

The control identifier (for example, a 1-bit identifier) may indicatethat a 242-type RU has been used. In other words, the control identifiermay indicate that a 242-RU, a 484-RU, or a 996-RU is included. If thetransmission frequency band in which a PPDU is transmitted has abandwidth of 20 MHz, a 242-RU is a single RU corresponding to the fullbandwidth of the transmission frequency band (namely, 20 MHz).Accordingly, the control identifier (for example, 1-bit identifier) mayindicate whether a single RU corresponding to the full bandwidth of thetransmission frequency band is allocated.

For example, if the transmission frequency band has a bandwidth of 40MHz, the control identifier (for example, a 1-bit identifier) mayindicate whether a single RU corresponding to the full bandwidth(namely, bandwidth of 40 MHz) of the transmission frequency band hasbeen allocated. In other words, the control identifier may indicatewhether a 484-RU has been allocated for transmission in the frequencyband with a bandwidth of 40 MHz.

For example, if the transmission frequency band has a bandwidth of 80MHz, the control identifier (for example, a 1-bit identifier) mayindicate whether a single RU corresponding to the full bandwidth(namely, bandwidth of 80 MHz) of the transmission frequency band hasbeen allocated. In other words, the control identifier may indicatewhether a 996-RU has been allocated for transmission in the frequencyband with a bandwidth of 80 MHz.

Various technical effects may be achieved through the control identifier(for example, 1-bit identifier).

First of all, when a single RU corresponding to the full bandwidth ofthe transmission frequency band is allocated through the controlidentifier (for example, a 1-bit identifier), allocation information ofthe RU may be omitted. In other words, since only one RU rather than aplurality of RUs is allocated over the whole transmission frequencyband, allocation information of the RU may be omitted deliberately.

Also, the control identifier may be used as signaling for full bandwidthMU-MIMO. For example, when a single RU is allocated over the fullbandwidth of the transmission frequency band, multiple users may beallocated to the corresponding single RU. In other words, even thoughsignals for each user are not distinctive in the temporal and spatialdomains, other techniques (for example, spatial multiplexing) may beused to multiplex the signals for multiple users in the same, single RU.Accordingly, the control identifier (for example, a 1-bit identifier)may also be used to indicate whether to use the full bandwidth MU-MIMOdescribed above.

The common field included in the second control field (HE-SIG-B, 740)may include an RU allocation subfield. According to the PPDU bandwidth,the common field may include a plurality of RU allocation subfields(including N RU allocation subfields). The format of the common fieldmay be defined as follows.

TABLE 8 Number Subfield of bits Description RU Allocation N × 8Indicates the RU assignment to be used in the data portion in thefrequency domain. It also indicates the number of users in each RU. ForRUs of size greater than or equal to 106-tones that support MU-MIMO, itindicates the number of users multiplexed using MU-MIMO. Consists of NRU Allocation subfields: N = 1 for a 20 MHz and a 40 MHz HE MU PPDU N =2 for an 80 MHz HE MU PPDU N = 4 for a 160 MHz or 80 + 80 MHz HE MU PPDUCenter 26-tone RU 1 This field is present only if (#15510) the value ofthe Band- width field of HE-SIG-A field in an HE MU PPDU is set togreater than 1. If the Bandwidth field of the HE-SIG-A field in an HE MUPPDU is set to 2, 4 or 5 for 80 MHz: Set to 1 to indicate that a user isallocated to the center 26- tone RU (see FIG. 28-7 (RU locations in an80 MHz HE PPDU(#16528))); otherwise, set to 0. The same value is appliedto both HE-SIG-B content channels. If the Bandwidth field of theHE-SIG-A field in an HE MU PPDU is set to 3,6 or 7 for 160 MHz or 80 +80 MHz: For HE-SIG-B content channel 1, set to 1 to indicate that a useris allocated to the center 26-tone RU of the lower fre- quency 80 MHz;otherwise, set to 0. For HE-SIG-B content channel 2, set to 1 toindicate that a user is allocated to the center 26-tone RU of the higherfre- quency 80 MHz; otherwise, set to 0. CRC 4 See 28.3.10.7.3 (CRCcomputation) Tail 6 Used to terminate the trellis of the convolutionaldecoder. Set to 0

The RU allocation subfield included in the common field of the HE-SIG-Bmay be configured with 8 bits and may indicate as follows with respectto 20 MHz PPDU bandwidth. RUs to be used as a data portion in thefrequency domain are allocated using an index for RU size anddisposition in the frequency domain. The mapping between an 8-bit RUallocation subfield for RU allocation and the number of users per RU maybe defined as follows.

TABLE 9 8 hits indices Number (B7 B6 B5 B4 of B3 B2 B1 B0) #1 #2 #3 #4#5 #6 #7 #8 #9 entries 00000000 26 26 26 26 26 26 26 26 26 1 00000001 2626 26 26 26 26 26 52 1 00000010 26 26 26 26 26 52 26 26 1 00000011 26 2626 26 26 52 52 1 00000100 26 26 52 26 26 26 26 26 1 00000101 26 26 52 2626 26 52 1 00000110 26 26 52 26 52 26 26 1 00000111 26 26 52 26 52 52 100001000 52 26 26 26 26 26 26 26 1 00001001 52 26 26 26 26 26 52 100001010 52 26 26 26 52 26 26 1 00001011 52 26 26 26 52 52 1 00001100 5252 26 26 26 26 26 1 00001101 52 52 26 26 26 52 1 00001110 52 52 26 52 2626 1 00001111 52 52 26 52 52 1 00010y₂y₁y₀ 52 52 — 106 8 00011y₂y₁y₀ 106— 52 52 8 00100y₂y₁y₀ 26 26 26 26 26 106 8 00101y₂y₁y₀ 26 26 52 26 106 800110y₂y₁y₀ 52 26 26 26 106 8 00111y₂y₁y₀ 52 52 26 106 8 01000y₂y₁y₀ 10626 26 26 26 26 8 01001y₂y₁y₀ 106 26 26 26 52 8 01010y₂y₁y₀ 106 26 52 2626 8 01011y₂y₁y₀ 106 26 52 52 8 0110y₁y₀z₁z₀ 106 — 106 16 01110000 52 52— 52 52 1 01110001 242-tone RU empty 1 01110010 484-tone RU with zeroUser fields 1 indicated in this RU Allocation subfield of the HE-SIG-Bcontent channel 01110011 996-tone RU with zero User fields 1 indicatedin this RU Allocation subfield of the HE-SIG-B content channel011101x₁x₀ Reserved 4 01111y₂y₁y₀ Reserved 8 10y₂y₁y₀z₂z₁z₀ 106 26 10664 11000y₂y₁y₀ 242 8 11001y₂y₁y₀ 484 8 11010y₂y₁y₀ 996 8 11011y₂y₁y₀Reserved 8 111x₄x₃x₂x₁x₀ Reserved 32 If(#Ed) signaling RUs of sizegreater than 242 subcarriers, y₂y₁y₀ = 000-111 indicates number of Userfields in the HE-SIG-B content channel that contains the corresponding8-bit RU Allocation subfield. Otherwise, y₂y₁y₀ = 000-111 indicatesnumber of STAs multiplexed in the 106-tone RU, 242-tone RU or the lowerfrequency 106-tone RU if there are two 106-tone RUs and one 26-tone RUis assigned between two 106-tone RUs. The binary vector y₂y₁y₀ indicates2² × y₂ + 2¹ × y₁ + y₀ + 1 STAs multiplexed the RU. z₂z₁z₀ = 000-111indicates number of STAs multiplexed in the higher frequency 106-tone RUif there are two 106-tone RUs and one 26-tone RU is assigned between two106-tone RUs. The binary vector z₂z₁z₀ indicates 2² × z₂ + 2¹ × z₁ +z₀ + 1 STAs multiplexed in the RU. Similarly, y₁y₀ = 00-11 indicatesnumber of STAs multiplexed in the lower frequency 106-tone RU. Thebinary vector y₁y₀ indicates 2¹ × y₁ + y₀ + 1 STAs multiplexed in theRU. Similarly, z₁z₀ = 00-11 indicates the number of STAs multiplexed inthe higher frequency 106-tone RU. The binary vector z₁z₀ indicates 2¹ ×z₁ + z₀ + 1 STAs multiplexed in the RU. #1 to #9 (from left to theright) is ordered in increasing order of the absolute frequency. x₁x₀ =00-11, x₄x₃x₂x₁x₀ = 00000-11111. ‘—’ means no STA in that RU.

The user-specific field included in the second control field (HE-SIG-B,740) may include a user field, a CRC field, and a Tail field. The formatof the user-specific field may be defined as follows.

TABLE 10 Num ber Sub- of field bits Description User N × The User fieldformat for a non-MU-MIMO allocation is field 21 defined in Table 28-26(User field format for a non-MU- MIMO allocation). The User field formatfor a MU-MIMO allocation is defined in Table 28-27 (User field for allMU- MIMO allocation). N = 1 if it is the last User Block field, and ifthere is only one user in the last User Block field. N = 2 otherwise.CRC 4 The CRC is calculated over bits 0 to 20 for a User Block fieldthat contains one User field, and bits 0 to 41 for a User Block fieldthat contains two User fields. See 28.3.10.7.3 (CRC computation). Tail 6Used to terminate the trellis of the convolutional decoder. Set to 0.

Also, the user-specific field of the HE-SIG-B is composed of a pluralityof user fields. The plurality of user fields are located after thecommon field of the HE-SIG-B. The location of the RU allocation subfieldof the common field and that of the user field of the user-specificfield are used together to identify an RU used for transmitting data ofan STA. A plurality of RUs designated as a single STA are now allowed inthe user-specific field. Therefore, signaling that allows an STA todecode its own data is transmitted only in one user field.

As an example, it may be assumed that the RU allocation subfield isconfigured with 8 bits of 01000010 to indicate that five 26-tone RUs arearranged next to one 106-tone RU and three user fields are included inthe 106-tone RU. At this time, the 106-tone RU may support multiplexingof the three users. This example may indicate that eight user fieldsincluded in the user-specific field are mapped to six RUs, the firstthree user fields are allocated according to the MU-MIMO scheme in thefirst 106-tone RU, and the remaining five user fields are allocated toeach of the five 26-tone RUs.

User fields included in the user-specific field of the HE-SIG-B may bedefined as described below. Firstly, user fields for non-MU-MIMOallocation are as described below.

TABLE 12 Number Bit Subfield of bits Description B0-B10 STA-ID 11 Set toa value of the element indicated from TXVEC- TOR parameter STA_ID_LIST(see 27.11.1 (STA_ID_LIST)). B11-B13 NSTS 3 Number of space-timestreams. Set to the number of space-time streams minus 1. B14 Beam- 1Use of transmit beamforming. formed Set to 1 if a beamforming steeringmatrix is applied to (#16038) the waveform in an SU transmission. Set to0 otherwise. B15-B18 MCS 4 Modulation and coding scheme Set to n forMCSn, where n = 0, 1 ,2 . . . , 11 Values 12 to 15 are reserved B19 DCM1 Indicates whether or not DCM is used. Set to 1 to indicate that thepayload(#Ed) of the cor- responding user of the HE MU PPDU is modulatedwith DCM for the MCS. Set to 0 to indicate that the payload of thecorre- sponding user of the PPDU is not modulated with DCM for the MCS.NOTE-DCM is not applied in combination with STBC.(#15664) B20 Coding 1Indicates whether BCC or LDPC is used. Set to 0 for BCC Set to 1 forLDPC NOTE If the STA-ID subfield is set to 2046, then the othersubfields can be set to arbitrary values.(#15946)

User fields for MU-MIMO allocation are as described below.

TABLE 13 Number Bit Subfield of bits Description B0-B10 STA-ID 11 Set toa value of element indicated from TXVECTOR parameter STA_ID_LIST (see27.11.1 (STA_ID_LIST)). B11-B14 Spatial Con- 4 Indicates the number ofspatial streams for a STA in an figuration MU-MIMO allocation (see Table28-28 (Spatial Con- figuration subfield encoding)). B15-B18 MCS 4Modulation and coding scheme. Set to n for MCSn, where n = 0, 1, 2, . .. , 11 Values 12 to 15 are reserved B19 Reserved 1 Reserved and set to 0B20 Coding 1 Indicates whether BCC or LDPC is used. Set to 0 for BCC Setto 1 for LDPC NOTE If the STA-ID subfield is set to 2046, then the othersubfields can be set to arbitrary values. (#15946)

FIG. 12 illustrates an example of an HE TB PPDU. The PPDU of FIG. 12illustrates an uplink PPDU transmitted in response to the trigger frameof FIG. 9. At least one STA receiving a trigger frame from an AP maycheck the common information field and the individual user informationfield of the trigger frame and may transmit a HE TB PPDU simultaneouslywith another STA which has received the trigger frame.

As shown in the figure, the PPDU of FIG. 12 includes various fields,each of which corresponds to the field shown in FIGS. 2, 3, and 7.Meanwhile, as shown in the figure, the HE TB PPDU (or uplink PPDU) ofFIG. 12 may not include the HE-SIG-B field but only the HE-SIG-A field.

1. CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance)

In IEEE 802.11, communication is achieved in a shared wireless medium,and thus has a characteristic fundamentally different from a wiredchannel environment. For example, communication is possible based oncarrier sense multiple access/collision detection (CSMA/CD) in the wiredchannel environment For example, when a signal is transmitted one timein Tx, the signal is transmitted to Rx without significant signalattenuation since a channel environment does not change much. In thiscase, when a collision occurs in two or more signals, it is detectable.This is because power detected in Rx is instantaneously greater thanpower transmitted in Tx. However, in a wireless channel environment, achannel is affected by various factors (e.g., a signal may besignificantly attenuated according to a distance or may instantaneouslyexperience deep fading), carrier sensing cannot be achieved correctly inTx as to whether a signal is properly transmitted in Rx in practice orwhether a collision exists. Therefore, a distributed coordinationfunction (DCF) which is a carrier sense multiple access/collisionavoidance (CSMA/CA) mechanism is introduced in 802.11. Herein, stations(STAs) having data to be transmitted perform clear channel assessment(CCA) for sensing a medium during a specific duration (e.g., DIFS: DCFinter-frame space) before transmitting the data. In this case, if themedium is idle, the STA can transmit the data by using the medium. Onthe other hand, if the medium is busy, under the assumption that severalSTAs have already waited for the use of the medium, the data can betransmitted after waiting by a random backoff period in addition to theDIFS. In this case, the random backoff period can allow the collision tobe avoidable because, under the assumption that there are several STAsfor transmitting data, each STA has a different backoff intervalprobabilistically and thus eventually has a different transmission time.When one STA starts transmission, the other STAs cannot use the medium.

The random backoff time and the procedure will be simply described asfollows. When a specific medium transitions from busy to idle, severalSTAs start a preparation for data transmission. In this case, tominimize a collision, the STAs intending to transmit the data selectrespective random backoff counts and wait by those slot times. Therandom backoff count is a pseudo-random integer value, and one ofuniform distribution values is selected in the range of [0 CW]. Herein,CW denotes a contention window. A CW parameter takes a CWmin value as aninitial value, and when transmission fails, the value is doubled. Forexample, if an ACK response is not received in response to a transmitteddata frame, it may be regarded that a collision occurs. If the CW valuehas a CWmax value, the CWmax value is maintained until data transmissionis successful, and when the data transmission is successful, is reset tothe CWmin value. In this case, the values CW, CWmin, and CWmax arepreferably maintained to 2^(n)−1 for convenience of implementations andoperations. Meanwhile, if the random backoff procedure starts, the STAselects the random backoff count in the [0 CW] range and thereaftercontinuously monitors a medium while counting down a backoff slot. Inthe meantime, if the medium enters a busy state, the countdown isstopped, and when the medium returns to an idle state, the countdown ofthe remaining backoff slots is resumed.

2. PHY Procedure

A PHY transmit/receive procedure in Wi-Fi is as follows, but a specificpacket configuration method may differ. For convenience, only 11n and11ax will be taken for example, but 11g/ac also conforms to a similarprocedure.

That is, in the PHY transmit procedure, a MAC protocol data unit (MPDU)or an aggregate MPDU (A-MPDU) transmitted from a MAC end is convertedinto a single PHY service data unit (PSDU) in a PHY end, and istransmitted by inserting a preamble, tail bits, and padding bits(optional), and this is called a PPDU.

The PHY receive procedure is usually as follows. When performing energydetection and preamble detection (L/HT/VHT/HE-preamble detection foreach WiFi version), information on a PSDU configuration is obtained froma PHY header (L/HT/VHT/HE-SIG) to read a MAC header, and then data isread.

3. Multi-Band (or Multi-Link) Aggregation

In order to increase a peak throughput, transmission of an increasedstream is considered in a WLAN 802.11 system by using a wider band ormore antennas compared to the legacy 11a. In addition, a method of usingvarious bands by aggregating the bands is also considered.

The present specification proposes a scheme of transmitting HE STAs anddata of the HE STAs simultaneously by using the same MU PPDU in asituation of considering a wide bandwidth, a multi-band (or multi-link)aggregation, or the like.

FIG. 13 shows multiple channels allocated in a 5 GHz band.

Hereinafter, a “band” may include, for example, 2.4 GHz, 5 GHz, and 6GHz bands. For example, the 2.4 GHz band and the 5 GHz band aresupported in the 11n standard, and up to the 6 GHz band is supported inthe 11ax standard. For example, in the 5 GHz band, multiple channels maybe defined as shown in FIG. 13.

The WLAN system to which technical features of the present specificationare applied may support a multi-band. That is, a transmitting STA cantransmit a PPDU through any channel (e.g., 20/40/80/80+80/160/240/320MHz, etc.) on a second band (e.g., 6 GHz) while transmitting the PPDUthrough any channel (e.g., 20/40/80/80+80/160 MHz, etc.) on a first band(e.g., 5 GHz) (In the present specification, a 240 MHz channel may be acontinuous 240 MHz channel or a combination of discontinuous 80/160 MHzchannels. Further, a 320 MHz channel may be a continuous 320 MHz channelor a combination of discontinuous 80/160 MHz channels. For example, inthe present document, the 20 MHz channel may be a continuous 240 MHzchannel, an 80+80+80 MHz channel, or an 80+160 MHz channel).

In addition, the multi-band described in the present document can beinterpreted in various meanings. For example, the transmitting STA mayset any one of 20/40/80/80+80/160/240/320 MHz channels on the 6 GHz bandto the first band, set any one of other 20/40/80/80+80/160/240/320 MHzchannels on the 6 GHz band to the second band, and may performmulti-band transmission (i.e., transmission simultaneously supportingthe first band and the second band). For example, the transmitting STAmay transmit the PPDU simultaneously through the first band and thesecond band, and may transmit it through only any one of the bands at aspecific timing.

At least any one of primary 20 MHz and secondary 20/40/80/160 MHzchannels described below may be transmitted in the first band, and theremaining channels may be transmitted in the second band. Alternatively,all channels may be transmitted in the same one band.

In the present specification, the term “band” may be replaced with“link”.

Next, a control signaling method for multi-band aggregation will bedescribed. Since the control signaling method may employ a fast sessiontransfer (FST) setup method, an FST setup protocol will be describedbelow.

The FST setup protocol consists of four states and a rule for a methodof transitioning from one state to a next state. The four states areInitial, Setup Completed, Transition Done, and Transition Confirmed. Inthe Initial state, an FST session operates in one or two bands/channels.In the Setup Complete state, an initiator and a responder are ready tochange band/channel(s) currently operating. The FST session may betransferred entirely or partially to another band/channel. TheTransition Done state allows the initiator and responder to operate indifferent bands/channels when a value of link loss timeout (LLT) is 0.Both the initiator and the responder shall communicate successfully in anew band/channel to reach the Transition Confirmed state. A statetransition diagram of the FST setup protocol is shown in FIG. 14.

FIG. 14 shows four states of the FST setup protocol.

FIG. 15 shows a procedure of the FST setup protocol.

FIG. 15 shows a procedure of the FST setup protocol for driving a statemachine shown in FIG. 14. The procedure of FIG. 15 is an example of abasic procedure, and does not cover all possible usages of the protocol.In FIG. 15, a MAC layer management entity (MLME) 1 and an MLME 2represent any two MLMEs of a device in which a multi-band is possibleaccording to a reference model described in a reference model for amulti-band operation. As will be described later, FST Setup Request andFST Setup Response frames are exchanged optionally in a repeated manneruntil an FST initiator and an FST responder move successfully in a SetupCompleted state. An operation of the procedure of the FST setup protocolis exemplified in FIG. 15.

In order to establish an FST session in an Initial state and to transferit in the Setup Completed state of the FST setup protocol, the initiatorand the responder shall exchange FST Setup Request and FST SetupResponse frames. The FST session exists in the Setup Completed state, aTransition Done state, or a Transition Confirmed state. In the Initialstate and the Setup Completed state, an old band/channel represents afrequency band/channel on which the FST session is transferred, and anew band/channel represents a frequency band/channel on which the FSTsession is transferred. In the Transition Done state, the newband/channel represents a frequency band/channel on which FST AckRequest and FST Ack Response frames are transmitted, and the oldband/channel represents a frequency band/channel on which the FSTsession is transferred.

If the responder accepts the FST Setup Request, a Status Code field isset to SUCCESS, and a Status Code is set to REJECTED WITH SUGGESTEDCHANGES.

Thus, one or more parameters of the FST Setup Request frame are invalid,and a replacement parameter shall be proposed. In addition, theresponder sets the Status Code field to PENDING_ADMITTING_FST_SESSION orPENDING_GAP_IN_BA_WINDOW to indicate that the FST Setup Request ispending, and sets the Status Code field to REQUEST_DECLINED to rejectthe FST Setup Request frame.

A responder which is an enabling STA sets a Status Code toREJECT_DSE_BAND and thus is initiated by a dependent STA which requeststo switch to a frequency band subject to a DSE procedure. Therefore, itis indicated that the FST Setup Request frame is rejected. In this case,if a responder is an enabling STA for the dependent STA, the respondermay indicate a duration in a TU before an FST setup starts with respectto the dependent STA by including a Timeout Interval element in the FSTSetup Response frame. A Timeout Interval Type field in the TimeoutInterval element shall be set to 4. The responder may use a parameter inthe FST Setup Request frame received from the dependent STA to initiatethe FST setup with respect to the initiator.

A responder which is a dependent STA and which is not enabled shallreject all FST Setup Request frames received for switching to afrequency band subject to the DSE procedure, except for a case where atransmitter of the FST setup Request frame is an enabling STA of thedependent STA.

4. Embodiment Applicable to the Present Disclosure

FIG. 16 shows an example of multi-band aggregation using a 2.4 GHz bandand a 5 GHz band.

Referring to FIG. 16, an AP and an STA may transmit/receive data byaggregating 2.4 GHz and 5 GHz bands. Regarding the multi-bandaggregation, the aggregation may be achieved in not only the 2.4/5 GHzband but also any band in the range of 1 to 7.125 GHz, and theaggregation may also be achieved in the same band (e.g., 5 GHz) by usingseveral RFs. Therefore, by using multi-band aggregation or several RFsin the same band, there is an opportunity to use not only a bandwidthused in the legacy 802.11 but also a bandwidth of at least 160 MHz(e.g., 320 MHz).

In order to perform contention in the structure of FIG. 16 in theconventional manner, backoff is performed on one 20 MHz primary channel(primary 20 or P20) determined irrespective of a multi-band, and atransmission bandwidth is determined by determining whether a secondarychannel is idle/busy during PIFS (or DIFS) before a moment (backoffcount=0) at which transmission is possible in the P20.

However, since a relatively wide bandwidth greater than or equal to 160MHz can be used, there may be a secondary channel having a widebandwidth such as a 160 MHz secondary channel (Secondary 160), a 320 MHzsecondary channel (Secondary 320), or the like. In particular, in acongested environment, there is a high possibility that the secondarychannel is busy, and thus a usability is significantly low. In addition,if CCA is performed on the secondary channel according to the existingCCA rule (Primary 20→Secondary 20→Secondary 40 . . . ), the existingrule cannot be used in a band aggregation combination (e.g., 120 MHz(40+80), 240 MHz (80+160), etc.), rather than a size in unit of20/40/80/160/320 MHz.

Accordingly, in order to solve the aforementioned problems, the presentspecification proposes a method of performing contention by providing aprimary channel for each band (or RF).

5. Proposed Embodiment

FIG. 17 shows an example in which a primary channel exists in each band(or RF) when performing multi-band aggregation.

When 160 MHz of a 5 GHz band and 160 MHz of a 6 GHz band are aggregatedas shown in FIG. 17, P20 exists in each band. The P20 may existirrespective of a bandwidth size (but, it is greater than or equal to 20MHz) applied in each band (RF).

Basically, in a Wi-Fi system, data transmission starts when a backoffcount (BC) value is 0 after contention is performed on each accesscategory (AC). However, when there are many primary channels, that is,when a primary channel exists in each band (or RF), a new datatransmission method is required according to a BC application method.

5.1 Transmission Method in the Presence of Backoff Count for EachPrimary Channel

When BC exists for each primary channel, at least one P20 (primary 20MHz) in a certain slot boundary may have a BC value of 0 (in atransmission-enabled state). In this case, a method of adjusting a BCvalue of the P20 and transmitting data is as follows, according to achannel state during a specific period (e.g., PIFS, AIFS, one slot) orthe P20 in which a BC value is not 0.

A. When channel state of P20 in which BC value is not 0 is idle

A1. Data is transmitted by setting BC value to 0

A2. Data is transmitted by maintaining BC value

-   -   In case of the method A1/A2, even a channel in which BC is not        yet 0 is used in data transmission, so that more data is        transmitted rapidly to increase efficiency of band aggregation,        whereas a collision probability may increase. In particular,        since the method A1 is a method which ignores the existing BC,        the collision probability may further increase.

A3. BC value is decreased, and data is not transmitted

-   -   Since a probability that BC of each band is 0 at the same time        is low, a band aggregation efficiency may be significantly        decreased if data is not transmitted.

B. When channel state of P20 in which BC value is not 0 is busy

B1. Only BC value is maintained

B2. The BC value is maintained, puncturing is performed on P20, and datais transmitted on a secondary channel which is idle during a specificperiod (e.g., PIFS, AIFS, one slot).

-   -   Although more data can be transmitted by additionally using the        secondary channel irrespective of a channel state of a primary        channel, a new rule of puncturing the primary channel shall be        added.

Based on the aforementioned method, for the idle case and the busy case,6 combinations may be used in total to adjust BC and transmit data (i.e.A1+B1, A1+B2, A2+B1, A2+B2, A3+B1, A3+B2).

Basically, in case of the methods A1 and A2, that is, at the moment atwhich data can be transmitted, whether data transmission is possible isdetermined by sensing the secondary channel during the PIFS (or DIFS)period in the conventional manner (e.g., 160 MHz (no preamblepuncturing): S20→S40→S80). However, a time interval for viewing a stateof the secondary channel may be different for each band (or RF). Inaddition, a preamble puncturing method for 80 MHz/160 MHz of 11ax mayalso be used.

FIG. 18 shows a BC adjusting method according to the method A1.

FIG. 19 shows an example of a method of transmitting data according tothe method A1+B1.

FIG. 18 and FIG. 19 show an example for the method A1+B1 when 3 bands,i.e., 40 MHz of a 2.4 GHz band, 160 MHz of a 5 GHz band, and 80 MHz of a6 GHz band, are aggregated. First, as shown in FIG. 18, if a channelstate of P20 of the 6 GHz band is determined as idle and thus B=0, since5 GHz P20 is idle during a PIFS period, BC is set from 4 to 0, and the 5GHz and 6 GHz bands are in a transmission-enabled state. Since 2.4 GHzP20 is busy during the PIFS period, BC remains intact. Therefore, FIG.19 shows an example of sensing a secondary channel during a PIFS periodin 5 GHz and 6 GHz bands. In case of 5 GHz, up to S40 is idle and thus atotal bandwidth of 80 MHz can be utilized, and in case of 6 GHz, up toS40 is idle and thus a total bandwidth of 80 MHz can be utilized.Therefore, an STA transmits data by utilizing 160 MHz through multi-bandaggregation, and receives (Block) ACK in an allocated band (160 MHz).

FIG. 20 shows an example of a BC adjusting method according to themethod A1, in the presence of 2 RFs.

FIG. 21 shows an example of a method of transmitting data according tothe method A1+B1, in the presence of 2 RFs.

FIG. 20 and FIG. 21 show an example for the method A1+B1 when 2 RFs(80+80) of a 5 GHz band are aggregated. First, as shown in FIG. 20, if achannel state of P20 of a 5 GHz RF 2 is determined as idle and thus B=0,since P20 of a 5 GHz RF 1 is idle during a PIFS period, BC is set from 3to 0, and the RF 1 and the RF 2 are in a transmission-enabled state.Therefore, FIG. 21 shows an example of sensing a secondary channelduring a PIFS period in each RF. In case of the 5 GHz RF 1, up to S20 isidle and thus a total bandwidth of 40 MHz can be utilized, and in caseof the 5 GHz RF 2, up to S40 is idle and thus a total bandwidth of up to80 MHz can be utilized. Therefore, an STA transmits data by utilizing120 MHz through multi-band aggregation, and receives (Block) ACK in anallocated band (120 MHz).

FIG. 22 shows an example of a BC adjusting method according to themethod A1, in case of a multi-band in the presence of 2 RFs.

FIG. 23 shows an example of a method of transmitting data according tothe method A1+B1, in case of a multi-band in the presence of 2 RFs.

FIG. 22 and FIG. 23 show an example for the method A1+B1 when 2 RFs(80+80) of a 5 GHz band are aggregated. First, as shown in FIG. 22, if achannel state of P20 of a 5 GHz RF 2 is determined as idle and thus B=0,since P20 of a 5 GHz RF 1 is idle during a PIFS period, BC is set from 3to 0, and since P20 of 6 GHz is also idle during the PIFS period, BC isset from 5 to 0. Herein, the RF 1 and RF 2 of 5 GHz and the 6 GHz bandare in a transmission-enabled state. Therefore, FIG. 23 shows an exampleof sensing a secondary channel during a PIFS period in 6 GHz and each RFof 5 GHz. In case of the 5 GHz RF 1, up to S20 is idle and thus a totalbandwidth of 40 MHz can be utilized. In case of the 5 GHz RF 2, up toS40 is idle and thus a total bandwidth of up to 80 MHz can be utilized.In case of 6 GHz, up to S40 is idle and thus a total bandwidth of 80 MHzcan be utilized. Therefore, an STA transmits data by utilizing 200 MHzthrough multi-band aggregation, and receives (Block) ACK in an allocatedband (200 MHz).

FIG. 24 shows an example of a method of transmitting data according tothe method A1+B1, including 80 MHz preamble puncturing.

FIG. 24 shows an example for the method A1+B1, including 80 MHz preamblepuncturing when 3 bands, i.e., 40 MHz of a 2.4 GHz band, 160 MHz of a 5GHz band, and 80 MHz of a 6 GHz band, are aggregated based on the resultof FIG. 18. Therefore, since 2.4 GHz P20 is busy during a PIFS period,BC remains intact. In case of 5 GHz, up to S40 is idle during the PIFSperiod and thus a total bandwidth of 80 MHz can be utilized. In case of6 GHz, up to S20 is busy but the S40 in the idle state can be usedthrough preamble puncturing and thus a total bandwidth of 60 MHz can beutilized. Therefore, an STA transmits data by utilizing 140 MHz throughmulti-band aggregation, and receives (Block) ACK in an allocated band(140 MHz).

FIG. 25 shows an example of a method of transmitting data according tothe method A1+B1, including 160 MHz preamble puncturing.

FIG. 25 shows an example for the method A1+B1, including 160 MHzpreamble puncturing when 3 bands, i.e., 40 MHz of a 2.4 GHz band, 160MHz of a 5 GHz band, and 80 MHz of a 6 GHz band, are aggregated based onthe result of FIG. 18. Therefore, since 2.4 GHz P20 is busy during aPIFS period, BC remains intact. In case of 5 GHz, S40 is busy during thePIFS period but S20 and S80 are idle, and thus a total bandwidth of 120MHz can be utilized through preamble puncturing. In case of 6 GHz, up toS40 is idle during the PIFS period and thus a total bandwidth of 80 MHzcan be utilized. Therefore, an STA transmits data by utilizing 200 MHzthrough multi-band aggregation, and receives (Block) ACK in an allocatedband (200 MHz).

FIG. 26 shows an example of a method of transmitting data according tothe method A1+B2.

FIG. 26 shows an example for the method A1+B1 when 3 bands, i.e., 40 MHzof a 2.4 GHz band, 160 MHz of a 5 GHz band, and 80 MHz of a 6 GHz band,are aggregated. This example is based on the result of FIG. 18.Therefore, P20 of 2.4 GHz is currently in a busy state during a PIFSperiod, and P20 of 2.4 GHz is punctured according to the method B2,thereby sensing a secondary channel. Since S20 is idle, the secondarychannel can be used in data transmission. As a result, a bandwidth of 20MHz at 2.4 GHz, a bandwidth of 80 MHz at 5 GHz, and a bandwidth of 80MHz at 6 GHz can be utilized. Therefore, an STA transmits data byutilizing 180 MHz through multi-band aggregation, and receives (Block)ACK in an allocated band (180 MHz).

FIG. 27 shows an example of a method of transmitting data according tothe method A1+B2, including 160 MHz preamble puncturing.

FIG. 27 shows an example for the method A1+B1, including 160 MHzpreamble puncturing, when 3 bands, i.e., 80 MHz of a 2.4 GHz band, 160MHz of a 5 GHz band, and 80 MHz of a 6 GHz band, are aggregated. Thisexample is based on the result of FIG. 3. Therefore, P20 of 2.4 GHz iscurrently in a busy state during a PIFS period, and P20 of 2.4 GHz ispunctured according to the method B2, thereby sensing a secondarychannel. Since S20 is idle, the secondary channel can be used in datatransmission. At 5 GHz, 20 MHz bands of S40 are respectively busy andidle during the PIFS period, and thus the 20 MHz band in the idle statecan be used through preamble puncturing. As a result, a bandwidth of 20MHz at 2.4 GHz, a bandwidth of 140 MHz at 5 GHz, and a bandwidth of 80MHz at 6 GHz can be utilized. Therefore, an STA transmits data byutilizing 240 MHz through multi-band aggregation, and receives (Block)ACK in an allocated band (240 MHz).

5.2. When Only One Backoff Count Exists for Multiple Primary Channels

Regardless of the presence of multiple primary channels, if only one BCis maintained in common, data may be transmitted when a BC value is 0.In this case, a data transmission method of each P20 is as follows,according to a channel state during a specific period (e.g., PIFS, AIFS,one slot) of each P20.

C. Data is transmitted only on P20 in which channel state is idle

-   -   Since transmission is performed only for an idle case, a        collision probability is low, but a bandwidth of a band in which        P20 is busy cannot be utilized.

D. Puncturing is performed on P20 in which a channel state is busy, anddata is transmitted on a secondary channel which is idle during aspecific period (e.g., PIFS, AIFS, one slot).

-   -   Although more data can be transmitted by additionally using the        secondary channel regardless of a primary channel, a new rule of        puncturing the primary channel shall be added.

Basically, in case of the method C, that is, at the moment at which datacan be transmitted, whether data transmission is possible is determinedby sensing the secondary channel during the PIFS (or DIFS) period in theconventional manner (e.g., 160 MHz (no preamble puncturing):S20→S40→S80). However, a time interval for viewing a state of thesecondary channel may be different for each band (or RF). In addition, apreamble puncturing method for 80 MHz/160 MHz of 11ax may also be used.

FIG. 28 shows an example of a method of transmitting data according tothe method C.

FIG. 28 shows an example for the transmission method C, at the moment ofBC=0, when 3 bands, i.e., 40 MHz of a 2.4 GHz band, 80 MHz of a 5 GHzband, and 80 MHz of a 6 GHz band, are aggregated. Referring to FIG. 28,when BC=0, during a PIFS period, P20 of 2.4 GHz is busy, P20 of 5 GHz isidle, and P20 of 6 GHz is idle, and it shows an example in which asecondary channel is sensed in the 5 GHz and 6 GHz bands by using thePIFS according to the transmission method C. In case of 5 GHz, up to S40is idle and thus a total bandwidth of 80 MHz can be utilized, and incase of 6 GHz, up to S20 is idle and thus a total bandwidth of 40 MHzcan be utilized. Therefore, an STA transmits data by utilizing 120 MHzthrough multi-band aggregation, and receives (Block) ACK in an allocatedband (120 MHz).

FIG. 29 shows an example of a method of transmitting data according tothe method C in the presence of 2 RFs.

FIG. 29 shows an example for the transmission method C, at the moment ofBC=0, when 2 RFs of a 5 GHz band are aggregated. Referring to FIG. 29,when BC=0, during a PIFS period, P20 of each RF is idle, and it shows anexample in which a secondary channel is sensed in each RF by using thePIFS according to the transmission method C. In case of the 5 GHz RF 1,up to S20 is idle and thus a total bandwidth of 40 MHz can be utilized,and in case of the 5 GHz RF 2, up to S20 is idle and thus a totalbandwidth of up to 40 MHz can be utilized. Therefore, an STA transmitsdata by utilizing 80 MHz through multi-band aggregation, and receives(Block) ACK in an allocated band (80 MHz).

FIG. 30 shows an example of a method of transmitting data according tothe method C, including 80 MHz preamble puncturing.

FIG. 30 shows an example for the transmission method C, including 80 MHzpreamble puncturing, at the moment of BC=0, when 3 bands, i.e., 40 MHzof a 2.4 GHz band, 80 MHz of a 5 GHz band, and 80 MHz of a 6 GHz band,are aggregated. Referring to FIG. 30, when BC=0, during a PIFS period,P20 of 2.4 GHz is busy, P20 of 5 GHz is idle, and P20 of 6 GHz is idle,and it shows an example in which a secondary is sensed by using PIFS inthe 5 GHz and 6 GHz banes according to the transmission method C. Incase of 5 GHz, S20 is busy but the S40 in the idle state can be usedthrough preamble puncturing, and thus a total bandwidth of 60 MHz can beutilized. In case of 6 GHz, up to S20 is idle and thus a total bandwidthof 40 MHz can be utilized. Therefore, an STA transmits data by utilizing100 MHz through multi-band aggregation, and receives (Block) ACK in anallocated band (100 MHz).

FIG. 31 shows an example of a method of transmitting data according tothe method D.

FIG. 31 shows an example for the transmission method D, at the moment ofBC=0, when 3 bands, i.e., 40 MHz of a 2.4 GHz band, 80 MHz of a 5 GHzband, and 80 MHz of a 6 GHz band, are aggregated. Referring to FIG. 31,when BC=0, during a PIFS period, P20 of 2.4 GHz is busy, P20 of 5 GHz isidle, and P20 of 6 GHz is idle. P20 of 2.4 GHz is punctured according tothe method D, thereby sensing a secondary channel. Since S20 is idleduring the PIFS, the secondary channel can be used in data transmission.As a result, a bandwidth of 20 MHz at 2.4 GHz, a bandwidth of 80 MHz at5 GHz, and a bandwidth of 40 MHz at 6 GHz can be utilized. Therefore, anSTA transmits data by utilizing 140 MHz through multi-band aggregation,and receives (Block) ACK in an allocated band (140 MHz).

FIG. 32 shows an example of a method of transmitting data according tothe method D, including 80 MHz preamble puncturing.

FIG. 32 shows an example for the transmission method D, including 80 MHzpreamble puncturing, at the moment of BC=0, when 3 bands, i.e., 40 MHzof a 2.4 GHz band, 80 MHz of a 5 GHz band, and 80 MHz of a 6 GHz band,are aggregated. Referring to FIG. 32, when BC=0, during a PIFS period,P20 of 2.4 GHz is busy, P20 of 5 GHz is idle, and P20 of 6 GHz is idle.P20 of 2.4 GHz is punctured according to the method D, thereby sensing asecondary channel. Since S20 is idle during the PIFS, the secondarychannel can be used in data transmission. In case of 5 GHz, S20 is busy,but the S40 in the idle state can be used through preamble puncturing.As a result, a bandwidth of 20 MHz at 2.4 GHz, a bandwidth of 60 MHz at5 GHz, and a bandwidth of 40 MHz at 6 GHz can be utilized. Therefore, anSTA transmits data by utilizing 120 MHz through multi-band aggregation,and receives (Block) ACK in an allocated band (120 MHz).

Hereinafter, the aforementioned embodiment will be described withreference to FIG. 14 to FIG. 32.

FIG. 33 is a flowchart illustrating a procedure of transmitting data ina transmitting device according to the present embodiment.

An example of FIG. 33 may be performed in a network environment in whicha next-generation WLAN system is supported. The next-generation WLANsystem is a WLAN system evolved from an 802.11ax system, and may satisfybackward compatibility with the 802.11ax system.

The example of FIG. 33 may be performed in the transmitting device, andthe transmitting device may correspond to an STA supporting an extremelyhigh throughput (EHT) WLAN system. The receiving device of FIG. 33 maycorrespond to an AP.

In step S3310, the transmitting device receives setup information on amulti-band in which first to third bands are aggregated.

In step S3320, the transmitting device performs channel sensing on thefirst band to the third band.

In step S3330, the transmitting device transmits the data to thereceiving device, based on a result of the channel sensing.

The first band includes a first primary channel and a first secondarychannel, the second band includes a second primary channel and a secondsecondary channel, and the third band includes a third primary channeland a third secondary channel.

The first band may be a 2.4 GHz band, the second band may be a 5 GHzband, and the third band may be a 6 GHz band.

Although a case where a multi-band is combination of three bands, i.e.,a triple band, is described in the present embodiment, theaforementioned band configuration is only one example, and the WLANsystem may support a variety of number of bands and channels. That is,the present embodiment may also include a case where the multi-band iscombination of two bands and a case where one band is divided into RFsto combine bands supported by respective RFs.

If the first primary channel is busy and a first backoff count (BC)value is not 0, the first BC value is maintained.

If the second primary channel is idle and a second BC value is not 0,the second BC value is set to 0, and the channel sensing is performed onthe second secondary channel.

If the third primary channel is idle and a third BC value is 0, thechannel sensing is performed on the third secondary channel.

For example, if the secondary channel is idle and the third secondarychannel is idle, the data may be transmitted through the second andthird primary channels and the second and third secondary channels. Thatis, the data may be transmitted by aggregating idle channels in thefirst to third bands.

As another example, the third secondary channel may include a firstchannel and a second channel. In this case, if the first channel is busyand the second channel is idle, the first channel may be punctured, andthe data may be transmitted through the second and third primarychannels, the second secondary channel, and the second channel. That is,the data may be transmitted by aggregating idle channels in the first tothird bands. That is, the data may be transmitted by aggregating idlechannels other than the punctured channel in the first to third bands.

As another example, if the first primary channel is busy and the firstBC value is not 0, the first primary channel may be punctured, andchannel sensing may performed on the first secondary channel. If thefirst secondary channel is idle, the data may be transmitted through thefirst secondary channel, the second and third primary channels, and thesecond and third secondary channels. That is, the data may betransmitted by aggregating idle channels other than the puncturedchannel in the first to third bands.

The channel sensing may be performed on the first to third primarychannels and the first to third secondary channels for a pre-setduration. The pre-set duration may be set to a PIFS (PCF (PointCoordination Function) Inter Frame Space), an AIFS (Arbitration InterFrame Space), or one slot.

As another example, the second band may be generated by aggregating afourth band supported by a first radio frequency (RF) and a fifth bandsupported by a second RF. That is, each band may be aggregated bydividing the same band into 2 RFs.

The fourth band may include a fourth primary channel and a fourthsecondary channel, and the fifth band may include a fifth primarychannel and a fifth secondary channel.

If the fourth primary channel is idle and the fourth BC value is not 0,the fourth BC may be set to 0, and the channel sensing may be performedon the fourth secondary channel. If the fifth primary channel is idleand the fifth BC value is 0, the channel sensing may be performed on thefifth secondary channel.

If the fourth secondary channel is idle and the fifth secondary channelis idle, the data may be transmitted through the third primary channel,the third secondary channel, the fourth and fifth primary channels, andthe fourth and fifth secondary channels. That is, idle channels may beaggregated in the first to third bands to transmit the data.

Likewise, the channel sensing may be performed during a pre-set periodfor the fourth to fifth secondary channels. The pre-set period may beset to PIFS (PCF (Point Coordination Function) Inter Frame Space), AIFS(Arbitration Inter Frame Space), or one slot.

In summary, the aforementioned embodiment describes a channel sensingand data transmission method in the presence of BC for each primarychannel.

In a first embodiment, if a primary channel of a specific band is in anidle state but a BC value is not 0, a transmitting device may transmitdata by setting the BC value to 0. The first embodiment may be appliedto the second primary channel. Since the BC value is directly set to 0,there may be a problem in fairness. Advantageously, however, the datacan be directly transmitted in the channel.

In a second embodiment, if the primary channel of the specific band isin an idle state but the BC value is not 0, the transmitting device maytransmit the data by maintaining the BC value. The second embodiment isan embodiment which is not applied to the first to third primarychannels, and a collision probability may increase since data istransmitted even if the BC value is not 0.

In a third embodiment, if the primary channel of the specific band is ina busy state and the BC value is not 0, the transmitting device may nottransmit the data by maintaining the BC value. That is, as in theconventional manner, the transmitting device may persistently wait untilthe BC value is 0 and, when the BC value is 0, may transmit data if thechannel is in the idle state. The third embodiment may be applied to thefirst primary channel. In addition, the third primary channel is also ina state where data can be directly transmitted since the BC value is 0,and thus it can be said that the third embodiment is applied.

In a fourth embodiment, if the primary channel of the specific band isin the busy state and the BC value is not 0, the transmitting device maytransmit the data by maintaining the BC value, by performing puncturingon the primary channel and performing channel sensing on a secondarychannel. Accordingly, when the secondary channel is idle even if theprimary channel is busy, data may be transmitted in a correspondingband, thereby increasing efficiency of the band. In case of a firstchannel and second channel included in the third secondary channel, thefourth embodiment may be applied.

The first BC value may be selected in a first contention window (CW)determined for the first primary channel. The second BC value may beselected in a second CW determined for the second primary channel. Thethird BC value may be selected in a third CW determined for the thirdprimary channel. The fourth BC value may be selected in a fourth CWdetermined for the fourth primary channel. The fifth BC value may beselected in a fifth CW determined for the fifth primary channel.

The transmitting device may receive Block Ack (BA) for the data. The BAmay be received through the same channel as the channel on which thedata is transmitted.

Hereinafter, a signaling scheme for multi-band aggregation will bedescribed. It is described in the present embodiment that setupinformation on a multi-band is received, and signaling may be performedby employing an FST setup scheme.

The transmitting device may transmit a multi-band setup request frame tothe receiving device. The transmitting device may receive a multi-bandsetup response frame from the receiving device.

The transmitting device may transmit a multi-band Ack request frame tothe receiving device. The transmitting device may receive a multi-bandAck response frame from the receiving device.

The transmitting device may include a first station management entity(SME), a first MAC layer management entity (MLME), and a second MLME.The receiving device may include a second SME, a third MLME, and afourth MLME.

The first MLME and the third MLME may be entities supporting the firstband, and the second MLME and the fourth MLME may be entities supportingthe second band.

The multi-band setup request frame and the multi-band setup responseframe may be transmitted/received between the first MLME and the thirdMLME. The multi-band Ack request frame and the multi-band Ack responseframe may be transmitted/received between the second MLME and the fourthMLME.

The first and second SMEs may generate a primitive including amulti-band parameter. The multi-band parameter may include a channelnumber, operating class, and band identifier (ID) designated in themulti-band. The primitive may be transferred to the first to fourthMLMEs.

The multi-band setup scheme includes four states when employing the FSTsetup scheme, and consists of a rule for a method of transitioning fromone state to a next state. The four states are Initial, Setup Completed,Transition Done, and Transition Confirmed.

In the Initial state, the transmitting device and the receiving devicecommunicate in an old band/channel. In this case, upontransmitting/receiving the FST setup request frame and the FST setupresponse frame between the transmitting device and the receiving device,a transition is made to the Setup Complete state, and the transmittingdevice and the receiving device are ready to change a band/channel(s)currently operating. An FST session may be entirely or partiallytransferred to another band/channel.

If a value of LLT included in the FST setup request frame is 0, atransition is made from the Setup Complete state to the Transition Donestate, and the transmitting device and the receiving device may operatein another band/channel.

Both the transmitting device and the receiving device shall communicatesuccessfully in a new band/channel to reach the Transition Confirmedstate. In this case, upon transmitting/receiving the FST Ack requestframe and the FST Ack response frame between the transmitting device andthe receiving device, a transition is made to the Transition Confirmedstate, and the transmitting device and the receiving device establish acomplete connection in the new band/channel.

FIG. 34 is a flowchart illustrating a procedure of receiving data in areceiving device according to the present embodiment.

An example of FIG. 34 may be performed in a network environment in whicha next-generation WLAN system is supported. The next-generation WLANsystem is a WLAN system evolved from an 802.11ax system, and may satisfybackward compatibility with the 802.11ax system.

The example of FIG. 34 may be performed in the receiving device, and maycorrespond to an AP. A transmitting device of FIG. 34 may correspond toan STA supporting an extremely high throughput (EHT) WLAN system.

In step S3410, the receiving device transmits setup information on amulti-band in which first to third bands are aggregated.

In step S3420, the receiving device receives the data from thetransmitting device. In this case, the data may be transmitted based onchannel sensing on the first band to the third band.

The first band includes a first primary channel and a first secondarychannel, the second band includes a second primary channel and a secondsecondary channel, and the third band includes a third primary channeland a third secondary channel.

The first band may be a 2.4 GHz band, the second band may be a 5 GHzband, and the third band may be a 6 GHz band.

Although a case where a multi-band is combination of three bands, i.e.,a triple band, is described in the present embodiment, theaforementioned band configuration is only one example, and the WLANsystem may support a variety of number of bands and channels. That is,the present embodiment may also include a case where the multi-band iscombination of two bands and a case where one band is divided into RFsto combine bands supported by respective RFs.

If the first primary channel is busy and a first backoff count (BC)value is not 0, the first BC value is maintained.

If the second primary channel is idle and a second BC value is not 0,the second BC value is set to 0, and the channel sensing is performed onthe second secondary channel.

If the third primary channel is idle and a third BC value is 0, thechannel sensing is performed on the third secondary channel.

For example, if the secondary channel is idle and the third secondarychannel is idle, the data may be transmitted through the second andthird primary channels and the second and third secondary channels. Thatis, the data may be transmitted by aggregating idle channels in thefirst to third bands.

As another example, the third secondary channel may include a firstchannel and a second channel. In this case, if the first channel is busyand the second channel is idle, the first channel may be punctured, andthe data may be transmitted through the second and third primarychannels, the second secondary channel, and the second channel. That is,the data may be transmitted by aggregating idle channels in the first tothird bands. That is, the data may be transmitted by aggregating idlechannels other than the punctured channel in the first to third bands.

As another example, if the first primary channel is busy and the firstBC value is not 0, the first primary channel may be punctured, andchannel sensing may performed on the first secondary channel. If thefirst secondary channel is idle, the data may be transmitted through thefirst secondary channel, the second and third primary channels, and thesecond and third secondary channels. That is, the data may betransmitted by aggregating idle channels other than the puncturedchannel in the first to third bands.

The channel sensing may be performed on the first to third primarychannels and the first to third secondary channels for a pre-setduration. The pre-set duration may be set to a PIFS (PCF (PointCoordination Function) Inter Frame Space), an AIFS (Arbitration InterFrame Space), or one slot.

As another example, the second band may be generated by aggregating afourth band supported by a first radio frequency (RF) and a fifth bandsupported by a second RF. That is, each band may be aggregated bydividing the same band into 2 RFs.

The fourth band may include a fourth primary channel and a fourthsecondary channel, and the fifth band may include a fifth primarychannel and a fifth secondary channel.

If the fourth primary channel is idle and the fourth BC value is not 0,the fourth BC may be set to 0, and the channel sensing may be performedon the fourth secondary channel. If the fifth primary channel is idleand the fifth BC value is 0, the channel sensing may be performed on thefifth secondary channel.

If the fourth secondary channel is idle and the fifth secondary channelis idle, the data may be transmitted through the third primary channel,the third secondary channel, the fourth and fifth primary channels, andthe fourth and fifth secondary channels. That is, idle channels may beaggregated in the first to third bands to transmit the data.

Likewise, the channel sensing may be performed during a pre-set periodfor the fourth to fifth secondary channels. The pre-set period may beset to PIFS (PCF (Point Coordination Function) Inter Frame Space), AIFS(Arbitration Inter Frame Space), or one slot.

In summary, the aforementioned embodiment describes a channel sensingand data transmission method in the presence of BC for each primarychannel.

In a first embodiment, if a primary channel of a specific band is in anidle state but a BC value is not 0, a transmitting device may transmitdata by setting the BC value to 0. The first embodiment may be appliedto the second primary channel. Since the BC value is directly set to 0,there may be a problem in fairness. Advantageously, however, the datacan be directly transmitted in the channel.

In a second embodiment, if the primary channel of the specific band isin an idle state but the BC value is not 0, the transmitting device maytransmit the data by maintaining the BC value. The second embodiment isan embodiment which is not applied to the first to third primarychannels, and a collision probability may increase since data istransmitted even if the BC value is not 0.

In a third embodiment, if the primary channel of the specific band is ina busy state and the BC value is not 0, the transmitting device may nottransmit the data by maintaining the BC value. That is, as in theconventional manner, the transmitting device may persistently wait untilthe BC value is 0 and, when the BC value is 0, may transmit data if thechannel is in the idle state. The third embodiment may be applied to thefirst primary channel. In addition, the third primary channel is also ina state where data can be directly transmitted since the BC value is 0,and thus it can be said that the third embodiment is applied.

In a fourth embodiment, if the primary channel of the specific band isin the busy state and the BC value is not 0, the transmitting device maytransmit the data by maintaining the BC value, by performing puncturingon the primary channel and performing channel sensing on a secondarychannel. Accordingly, when the secondary channel is idle even if theprimary channel is busy, data may be transmitted in a correspondingband, thereby increasing efficiency of the band. In case of a firstchannel and second channel included in the third secondary channel, thefourth embodiment may be applied.

The first BC value may be selected in a first contention window (CW)determined for the first primary channel. The second BC value may beselected in a second CW determined for the second primary channel. Thethird BC value may be selected in a third CW determined for the thirdprimary channel. The fourth BC value may be selected in a fourth CWdetermined for the fourth primary channel. The fifth BC value may beselected in a fifth CW determined for the fifth primary channel.

The transmitting device may receive Block Ack (BA) for the data. The BAmay be received through the same channel as the channel on which thedata is transmitted.

Hereinafter, a signaling scheme for multi-band aggregation will bedescribed. It is described in the present embodiment that setupinformation on a multi-band is received, and signaling may be performedby employing an FST setup scheme.

The transmitting device may transmit a multi-band setup request frame tothe receiving device. The transmitting device may receive a multi-bandsetup response frame from the receiving device.

The transmitting device may transmit a multi-band Ack request frame tothe receiving device. The transmitting device may receive a multi-bandAck response frame from the receiving device.

The transmitting device may include a first station management entity(SME), a first MAC layer management entity (MLME), and a second MLME.The receiving device may include a second SME, a third MLME, and afourth MLME.

The first MLME and the third MLME may be entities supporting the firstband, and the second MLME and the fourth MLME may be entities supportingthe second band.

The multi-band setup request frame and the multi-band setup responseframe may be transmitted/received between the first MLME and the thirdMLME. The multi-band Ack request frame and the multi-band Ack responseframe may be transmitted/received between the second MLME and the fourthMLME.

The first and second SMEs may generate a primitive including amulti-band parameter. The multi-band parameter may include a channelnumber, operating class, and band identifier (ID) designated in themulti-band. The primitive may be transferred to the first to fourthMLMEs.

The multi-band setup scheme includes four states when employing the FSTsetup scheme, and consists of a rule for a method of transitioning fromone state to a next state. The four states are Initial, Setup Completed,Transition Done, and Transition Confirmed.

In the Initial state, the transmitting device and the receiving devicecommunicate in an old band/channel. In this case, upontransmitting/receiving the FST setup request frame and the FST setupresponse frame between the transmitting device and the receiving device,a transition is made to the Setup Complete state, and the transmittingdevice and the receiving device are ready to change a band/channel(s)currently operating. An FST session may be entirely or partiallytransferred to another band/channel.

If a value of LLT included in the FST setup request frame is 0, atransition is made from the Setup Complete state to the Transition Donestate, and the transmitting device and the receiving device may operatein another band/channel.

Both the transmitting device and the receiving device shall communicatesuccessfully in a new band/channel to reach the Transition Confirmedstate. In this case, upon transmitting/receiving the FST Ack requestframe and the FST Ack response frame between the transmitting device andthe receiving device, a transition is made to the Transition Confirmedstate, and the transmitting device and the receiving device establish acomplete connection in the new band/channel.

5. Device Configuration

FIG. 35 is a diagram describing a device for implementing theabove-described method.

A wireless device (100) of FIG. 35 may correspond to an initiator STA,which transmits a signal that is described in the description presentedabove, and a wireless device (150) may correspond to a responder STA,which receives a signal that is described in the description presentedabove. At this point, each station may correspond to a 11ay device (oruser equipment (UE)) or a PCP/AP. Hereinafter, for simplicity in thedescription of the present disclosure, the initiator STA transmits asignal is referred to as a transmitting device (100), and the responderSTA receiving a signal is referred to as a receiving device (150).

The transmitting device (100) may include a processor (110), a memory(120), and a transmitting/receiving unit (130), and the receiving device(150) may include a processor (160), a memory (170), and atransmitting/receiving unit (180). The transmitting/receiving unit (130,180) transmits/receives a radio signal and may be operated in a physicallayer of IEEE 802.11/3GPP, and so on. The processor (110, 160) may beoperated in the physical layer and/or MAC layer and may be operativelyconnected to the transmitting/receiving unit (130, 180).

The processor (110, 160) and/or the transmitting/receiving unit (130,180) may include application-specific integrated circuit (ASIC), otherchipset, logic circuit and/or data processor. The memory (120, 170) mayinclude read-only memory (ROM), random access memory (RAM), flashmemory, memory card, storage medium and/or other storage unit. When theembodiments are executed by software, the techniques (or methods)described herein can be executed with modules (e.g., processes,functions, and so on) that perform the functions described herein. Themodules can be stored in the memory (120, 170) and executed by theprocessor (110, 160). The memory (120, 170) can be implemented (orpositioned) within the processor (110, 160) or external to the processor(110, 160). Also, the memory (120, 170) may be operatively connected tothe processor (110, 160) via various means known in the art.

The processor 110, 160 may implement the functions, processes and/ormethods proposed in the present disclosure. For example, the processor110, 160 may perform the operation according to the present embodiment.

The operation of the processor 110 of the transmitting device isspecifically as follows. The processor 110 of the transmitting devicereceives setup information on a multi-band, and performs channel sensingon the multi-band to transmit data to the receiving device, based on aresult of the channel sensing.

The operation of the processor 160 of the receiving device isspecifically as follows. The processor 160 of the receiving devicetransmits setup information on a multi-band, and receives thetransmitted data through the multi-band, based on channel sensingperformed on the multi-band.

FIG. 36 shows a UE to which the technical features of the presentdisclosure can be applied.

A UE includes a processor 610, a power management module 611, a battery612, a display 613, a keypad 614, a subscriber identification module(SIM) card 615, a memory 620, a transceiver 630, one or more antennas631, a speaker 640, and a microphone 641.

The processor 610 may be configured to implement proposed functions,procedures and/or methods of the present disclosure described below. Theprocessor 610 may be configured to control one or more other componentsof the UE 600 to implement proposed functions, procedures and/or methodsof the present disclosure described below. Layers of the radio interfaceprotocol may be implemented in the processor 610. The processor 610 mayinclude application-specific integrated circuit (ASIC), other chipset,logic circuit and/or data processing device. The processor 610 may be anapplication processor (AP). The processor 610 may include at least oneof a digital signal processor (DSP), a central processing unit (CPU), agraphics processing unit (GPU), a modem (modulator and demodulator). Anexample of the processor 610 may be found in SNAPDRAGON™ series ofprocessors made by Qualcomm®, EXYNOS™ series of processors made bySamsung®, A series of processors made by Apple®, HELIO™ series ofprocessors made by MediaTek®, ATOM™ series of processors made by Intel®or a corresponding next generation processor.

The power management module 611 manages power for the processor 610and/or the transceiver 630. The battery 612 supplies power to the powermanagement module 611. The display 613 outputs results processed by theprocessor 610. The keypad 614 receives inputs to be used by theprocessor 610. The keypad 614 may be shown on the display 613. The SIMcard 615 is an integrated circuit that is intended to securely store theinternational mobile subscriber identity (IMSI) number and its relatedkey, which are used to identify and authenticate subscribers on mobiletelephony devices (such as mobile phones and computers). It is alsopossible to store contact information on many SIM cards.

The memory 620 is operatively coupled with the processor 610 and storesa variety of information to operate the processor 610. The memory 620may include read-only memory (ROM), random access memory (RAM), flashmemory, memory card, storage medium and/or other storage device. Whenthe embodiments are implemented in software, the techniques describedherein can be implemented with modules (e.g., procedures, functions, andso on) that perform the functions described herein. The modules can bestored in the memory 620 and executed by the processor 610. The memory620 can be implemented within the processor 610 or external to theprocessor 610 in which case those can be communicatively coupled to theprocessor 610 via various means as is known in the art.

The transceiver 630 is operatively coupled with the processor 610, andtransmits and/or receives a radio signal. The transceiver 630 includes atransmitter and a receiver. The transceiver 630 may include basebandcircuitry to process radio frequency signals. The transceiver 630controls the one or more antennas 631 to transmit and/or receive a radiosignal.

The speaker 640 outputs sound-related results processed by the processor610. The microphone 641 receives sound-related inputs to be used by theprocessor 610.

In case of a transmitting device, the processor 610 receives setupinformation on a multi-band, and performs channel sensing on themulti-band to transmit data to the receiving device, based on a resultof the channel sensing.

In case of a receiving device, the processor 610 transmits setupinformation on a multi-band, and receives the transmitted data throughthe multi-band, based on channel sensing performed on the multi-band.

The first band includes a first primary channel and a first secondarychannel, the second band includes a second primary channel and a secondsecondary channel, and the third band includes a third primary channeland a third secondary channel.

The first band may be a 2.4 GHz band, the second band may be a 5 GHzband, and the third band may be a 6 GHz band.

Although a case where a multi-band is combination of three bands, i.e.,a triple band, is described in the present embodiment, theaforementioned band configuration is only one example, and the WLANsystem may support a variety of number of bands and channels. That is,the present embodiment may also include a case where the multi-band iscombination of two bands and a case where one band is divided into RFsto combine bands supported by respective RFs.

If the first primary channel is busy and a first backoff count (BC)value is not 0, the first BC value is maintained.

If the second primary channel is idle and a second BC value is not 0,the second BC value is set to 0, and the channel sensing is performed onthe second secondary channel.

If the third primary channel is idle and a third BC value is 0, thechannel sensing is performed on the third secondary channel.

For example, if the secondary channel is idle and the third secondarychannel is idle, the data may be transmitted through the second andthird primary channels and the second and third secondary channels. Thatis, the data may be transmitted by aggregating idle channels in thefirst to third bands.

As another example, the third secondary channel may include a firstchannel and a second channel. In this case, if the first channel is busyand the second channel is idle, the first channel may be punctured, andthe data may be transmitted through the second and third primarychannels, the second secondary channel, and the second channel. That is,the data may be transmitted by aggregating idle channels in the first tothird bands. That is, the data may be transmitted by aggregating idlechannels other than the punctured channel in the first to third bands.

As another example, if the first primary channel is busy and the firstBC value is not 0, the first primary channel may be punctured, andchannel sensing may performed on the first secondary channel. If thefirst secondary channel is idle, the data may be transmitted through thefirst secondary channel, the second and third primary channels, and thesecond and third secondary channels. That is, the data may betransmitted by aggregating idle channels other than the puncturedchannel in the first to third bands.

The channel sensing may be performed on the first to third primarychannels and the first to third secondary channels for a pre-setduration. The pre-set duration may be set to a PIFS (PCF (PointCoordination Function) Inter Frame Space), an AIFS (Arbitration InterFrame Space), or one slot.

As another example, the second band may be generated by aggregating afourth band supported by a first radio frequency (RF) and a fifth bandsupported by a second RF. That is, each band may be aggregated bydividing the same band into 2 RFs.

The fourth band may include a fourth primary channel and a fourthsecondary channel, and the fifth band may include a fifth primarychannel and a fifth secondary channel.

If the fourth primary channel is idle and the fourth BC value is not 0,the fourth BC may be set to 0, and the channel sensing may be performedon the fourth secondary channel. If the fifth primary channel is idleand the fifth BC value is 0, the channel sensing may be performed on thefifth secondary channel.

If the fourth secondary channel is idle and the fifth secondary channelis idle, the data may be transmitted through the third primary channel,the third secondary channel, the fourth and fifth primary channels, andthe fourth and fifth secondary channels. That is, idle channels may beaggregated in the first to third bands to transmit the data.

Likewise, the channel sensing may be performed during a pre-set periodfor the fourth to fifth secondary channels. The pre-set period may beset to PIFS (PCF (Point Coordination Function) Inter Frame Space), AIFS(Arbitration Inter Frame Space), or one slot.

In summary, the aforementioned embodiment describes a channel sensingand data transmission method in the presence of BC for each primarychannel.

In a first embodiment, if a primary channel of a specific band is in anidle state but a BC value is not 0, a transmitting device may transmitdata by setting the BC value to 0. The first embodiment may be appliedto the second primary channel. Since the BC value is directly set to 0,there may be a problem in fairness. Advantageously, however, the datacan be directly transmitted in the channel.

In a second embodiment, if the primary channel of the specific band isin an idle state but the BC value is not 0, the transmitting device maytransmit the data by maintaining the BC value. The second embodiment isan embodiment which is not applied to the first to third primarychannels, and a collision probability may increase since data istransmitted even if the BC value is not 0.

In a third embodiment, if the primary channel of the specific band is ina busy state and the BC value is not 0, the transmitting device may nottransmit the data by maintaining the BC value. That is, as in theconventional manner, the transmitting device may persistently wait untilthe BC value is 0 and, when the BC value is 0, may transmit data if thechannel is in the idle state. The third embodiment may be applied to thefirst primary channel. In addition, the third primary channel is also ina state where data can be directly transmitted since the BC value is 0,and thus it can be said that the third embodiment is applied.

In a fourth embodiment, if the primary channel of the specific band isin the busy state and the BC value is not 0, the transmitting device maytransmit the data by maintaining the BC value, by performing puncturingon the primary channel and performing channel sensing on a secondarychannel. Accordingly, when the secondary channel is idle even if theprimary channel is busy, data may be transmitted in a correspondingband, thereby increasing efficiency of the band. In case of a firstchannel and second channel included in the third secondary channel, thefourth embodiment may be applied.

The first BC value may be selected in a first contention window (CW)determined for the first primary channel. The second BC value may beselected in a second CW determined for the second primary channel. Thethird BC value may be selected in a third CW determined for the thirdprimary channel. The fourth BC value may be selected in a fourth CWdetermined for the fourth primary channel. The fifth BC value may beselected in a fifth CW determined for the fifth primary channel.

The transmitting device may receive Block Ack (BA) for the data. The BAmay be received through the same channel as the channel on which thedata is transmitted.

Hereinafter, a signaling scheme for multi-band aggregation will bedescribed. It is described in the present embodiment that setupinformation on a multi-band is received, and signaling may be performedby employing an FST setup scheme.

The transmitting device may transmit a multi-band setup request frame tothe receiving device. The transmitting device may receive a multi-bandsetup response frame from the receiving device.

The transmitting device may transmit a multi-band Ack request frame tothe receiving device. The transmitting device may receive a multi-bandAck response frame from the receiving device.

The transmitting device may include a first station management entity(SME), a first MAC layer management entity (MLME), and a second MLME.The receiving device may include a second SME, a third MLME, and afourth MLME.

The first MLME and the third MLME may be entities supporting the firstband, and the second MLME and the fourth MLME may be entities supportingthe second band.

The multi-band setup request frame and the multi-band setup responseframe may be transmitted/received between the first MLME and the thirdMLME. The multi-band Ack request frame and the multi-band Ack responseframe may be transmitted/received between the second MLME and the fourthMLME.

The first and second SMEs may generate a primitive including amulti-band parameter. The multi-band parameter may include a channelnumber, operating class, and band identifier (ID) designated in themulti-band. The primitive may be transferred to the first to fourthMLMEs.

The multi-band setup scheme includes four states when employing the FSTsetup scheme, and consists of a rule for a method of transitioning fromone state to a next state. The four states are Initial, Setup Completed,Transition Done, and Transition Confirmed.

In the Initial state, the transmitting device and the receiving devicecommunicate in an old band/channel. In this case, upontransmitting/receiving the FST setup request frame and the FST setupresponse frame between the transmitting device and the receiving device,a transition is made to the Setup Complete state, and the transmittingdevice and the receiving device are ready to change a band/channel(s)currently operating. An FST session may be entirely or partiallytransferred to another band/channel.

If a value of LLT included in the FST setup request frame is 0, atransition is made from the Setup Complete state to the Transition Donestate, and the transmitting device and the receiving device may operatein another band/channel.

Both the transmitting device and the receiving device shall communicatesuccessfully in a new band/channel to reach the Transition Confirmedstate. In this case, upon transmitting/receiving the FST Ack requestframe and the FST Ack response frame between the transmitting device andthe receiving device, a transition is made to the Transition Confirmedstate, and the transmitting device and the receiving device establish acomplete connection in the new band/channel.

What is claimed is:
 1. A method of transmitting data in a wireless localarea network (WLAN) system, the method comprising: receiving, by atransmitting device, setup information on a multi-band in which first tothird bands are aggregated; performing, by the transmitting device,channel sensing on the first band to the third band; and transmitting,by the transmitting device, the data to a receiving device, based on aresult of the channel sensing, wherein the first band includes a firstprimary channel and a first secondary channel, wherein the second bandincludes a second primary channel and a second secondary channel,wherein the third band includes a third primary channel and a thirdsecondary channel, wherein, if the first primary channel is busy and afirst backoff count (BC) value is not 0, the first BC value ismaintained, wherein, if the second primary channel is idle and a secondBC value is not 0, the second BC value is set to 0, and the channelsensing is performed on the second secondary channel, and wherein, ifthe third primary channel is idle and a third BC value is 0, the channelsensing is performed on the third secondary channel.
 2. The method ofclaim 1, wherein, if the secondary channel is idle and the thirdsecondary channel is idle, the data is transmitted through the secondand third primary channels and the second and third secondary channels.3. The method of claim 1, wherein the third secondary channel includes afirst channel and a second channel, wherein, if the first channel isbusy and the second channel is idle, the first channel is punctured, andwherein the data is transmitted through the second and third primarychannels, the second secondary channel, and the second channel.
 4. Themethod of claim 1, wherein, if the first primary channel is busy and thefirst BC value is not 0, the first primary channel is punctured, andchannel sensing is performed on the first secondary channel, andwherein, if the first secondary channel is idle, the data is transmittedthrough the first secondary channel, the second and third primarychannels, and the second and third secondary channels.
 5. The method ofclaim 4, wherein the channel sensing is performed on the first to thirdprimary channels and the first to third secondary channels for a pre-setduration, and wherein the pre-set duration is set to a PIFS (PCF (PointCoordination Function) Inter Frame Space), an AIFS (Arbitration InterFrame Space), or one slot.
 6. The method of claim 1, wherein the secondband is generated by aggregating a fourth band supported by a firstradio frequency (RF) and a fifth band supported by a second RF, whereinthe fourth band includes a fourth primary channel and a fourth secondarychannel, wherein the fifth band includes a fifth primary channel and afifth secondary channel, wherein, if the fourth primary channel is idleand the fourth BC value is not 0, the fourth BC is set to 0, and thechannel sensing is performed on the fourth secondary channel, andwherein, if the fifth primary channel is idle and the fifth BC value is0, the channel sensing is performed on the fifth secondary channel. 7.The method of claim 6, wherein, if the fourth secondary channel is idleand the fifth secondary channel is idle, the data is transmitted throughthe third primary channel, the third secondary channel, the fourth andfifth primary channels, and the fourth and fifth secondary channels. 8.The method of claim 7, wherein the first BC value is selected in a firstcontention window (CW) determined for the first primary channel, whereinthe second BC value is selected in a second CW determined for the secondprimary channel, wherein the third BC value is selected in a third CWdetermined for the third primary channel, wherein the fourth BC value isselected in a fourth CW determined for the fourth primary channel, andwherein the fifth BC value is selected in a fifth CW determined for thefifth primary channel.
 9. The method of claim 2, further comprisingreceiving, by the transmitting device, Block Ack (BA) for the data,wherein the BA is received through the same channel as the channel onwhich the data is transmitted.
 10. The method of claim 1, wherein thereceiving of the setup information on the multi-band comprises:transmitting, by the transmitting device, a multi-band setup requestframe to the receiving device; receiving, by the transmitting device, amulti-band setup response frame from the receiving device; transmitting,by the transmitting device, a multi-band Ack request frame to thereceiving device; and receiving, by the transmitting device, amulti-band Ack response frame from the receiving device.
 11. The methodof claim 10, wherein the transmitting device includes a first stationmanagement entity (SME), a first MAC layer management entity (MLME), anda second MLME, wherein the receiving device includes a second SME, athird MLME, and a fourth MLME, wherein the first MLME and the third MLMEare entities supporting the first band, wherein the second MLME and thefourth MLME are entities supporting the second band, wherein themulti-band setup request frame and the multi-band setup response frameare transmitted/received between the first MLME and the third MLME,wherein the multi-band Ack request frame and the multi-band Ack responseframe are transmitted/received between the second MLME and the fourthMLME, wherein the first and second SMEs generate a primitive including amulti-band parameter, wherein the multi-band parameter includes achannel number, operating class, and band identifier (ID) designated inthe multi-band, and wherein the primitive is transferred to the first tofourth MLMEs.
 12. The method of claim 1, wherein the first band is a 2.4GHz band, wherein the second band is a 5 GHz band, and wherein the thirdband is a 6 GHz band.
 13. A transmitting device transmitting data in awireless local area network (WLAN) system, the transmitting devicecomprising: a memory; a transceiver; and a processor operatively coupledwith the memory and the transceiver, wherein the processor is configuredto: receive setup information on a multi-band in which first to thirdbands are aggregated; perform channel sensing on the first band to thethird band; and transmit the data to a receiving device, based on aresult of the channel sensing, wherein the first band includes a firstprimary channel and a first secondary channel, wherein the second bandincludes a second primary channel and a second secondary channel,wherein the third band includes a third primary channel and a thirdsecondary channel, wherein, if the first primary channel is busy and afirst backoff count (BC) value is not 0, the first BC value ismaintained, wherein, if the second primary channel is idle and a secondBC value is not 0, the second BC value is set to 0, and the channelsensing is performed on the second secondary channel, and wherein, ifthe third primary channel is idle and a third BC value is 0, the channelsensing is performed on the third secondary channel.
 14. Thetransmitting device of claim 13, wherein, if the secondary channel isidle and the third secondary channel is idle, the data is transmittedthrough the second and third primary channels and the second and thirdsecondary channels.
 15. The transmitting device of claim 13, wherein thethird secondary channel includes a first channel and a second channel,wherein, if the first channel is busy and the second channel is idle,the first channel is punctured, and wherein the data is transmittedthrough the second and third primary channels, the second secondarychannel, and the second channel.
 16. The transmitting device of claim13, wherein, if the first primary channel is busy and the first BC valueis not 0, the first primary channel is punctured, and channel sensing isperformed on the first secondary channel, and wherein, if the firstsecondary channel is idle, the data is transmitted through the firstsecondary channel, the second and third primary channels, and the secondand third secondary channels.
 17. The transmitting device of claim 16,wherein the channel sensing is performed on the first to third primarychannels and the first to third secondary channels for a pre-setduration, and wherein the pre-set duration is set to a PIFS (PCF (PointCoordination Function) Inter Frame Space), an AIFS (Arbitration InterFrame Space), or one slot.
 18. The transmitting device of claim 13,wherein the second band is generated by aggregating a fourth bandsupported by a first radio frequency (RF) and a fifth band supported bya second RF, wherein the fourth band includes a fourth primary channeland a fourth secondary channel, wherein the fifth band includes a fifthprimary channel and a fifth secondary channel, wherein, if the fourthprimary channel is idle and the fourth BC value is not 0, the fourth BCis set to 0, and the channel sensing is performed on the fourthsecondary channel, and wherein, if the fifth primary channel is idle andthe fifth BC value is 0, the channel sensing is performed on the fifthsecondary channel.
 19. The transmitting device of claim 18, wherein, ifthe fourth secondary channel is idle and the fifth secondary channel isidle, the data is transmitted through the third primary channel, thethird secondary channel, the fourth and fifth primary channels, and thefourth and fifth secondary channels.
 20. A method of receiving data in awireless local area network (WLAN) system, the method comprising:transmitting, by a receiving device, setup information on a multi-bandin which first to third bands are aggregated; and receiving, by thereceiving device, the data from a transmitting device, wherein the datais transmitted based on channel sensing on the first band to the thirdband, wherein the first band includes a first primary channel and afirst secondary channel, wherein the second band includes a secondprimary channel and a second secondary channel, wherein the third bandincludes a third primary channel and a third secondary channel, wherein,if the first primary channel is busy and a first backoff count (BC)value is not 0, the first BC value is maintained, wherein, if the secondprimary channel is idle and a second BC value is not 0, the second BCvalue is set to 0, and the channel sensing is performed on the secondsecondary channel, and wherein, if the third primary channel is idle anda third BC value is 0, the channel sensing is performed on the thirdsecondary channel.